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    <div class="titlepage">
      <div>
        <div>
          <h1 class="title"><a name="idm1" id="idm1"></a>Recoll
          user manual</h1>
        </div>
        <div>
          <div class="author">
            <h3 class="author"><span class=
            "firstname">Jean-Francois</span> <span class=
            "surname">Dockes</span></h3>
            <div class="affiliation">
              <div class="address">
                <p><code class="email">&lt;<a class="email" href=
                "mailto:jfd@recoll.org">jfd@recoll.org</a>&gt;</code></p>
              </div>
            </div>
          </div>
        </div>
        <div>
          <p class="copyright">Copyright © 2005-2019 Jean-Francois
          Dockes</p>
        </div>
        <div>
          <div class="abstract">
            <p><code class="literal">Permission is granted to copy,
            distribute and/or modify this document under the terms
            of the GNU Free Documentation License, Version 1.3 or
            any later version published by the Free Software
            Foundation; with no Invariant Sections, no Front-Cover
            Texts, and no Back-Cover Texts. A copy of the license
            can be found at the following location: <a class=
            "ulink" href="http://www.gnu.org/licenses/fdl.html"
            target="_top">GNU web site</a>.</code></p>
            <p>This document introduces full text search notions
            and describes the installation and use of the
            <span class="application">Recoll</span> application.
            This version describes <span class=
            "application">Recoll</span> 1.25.</p>
          </div>
        </div>
      </div>
      <hr>
    </div>
    <div class="toc">
      <p><b>Table of Contents</b></p>
      <dl class="toc">
        <dt><span class="chapter">1. <a href=
        "#RCL.INTRODUCTION">Introduction</a></span></dt>
        <dd>
          <dl>
            <dt><span class="sect1">1.1. <a href=
            "#RCL.INTRODUCTION.TRYIT">Giving it a
            try</a></span></dt>
            <dt><span class="sect1">1.2. <a href=
            "#RCL.INTRODUCTION.SEARCH">Full text
            search</a></span></dt>
            <dt><span class="sect1">1.3. <a href=
            "#RCL.INTRODUCTION.RECOLL">Recoll
            overview</a></span></dt>
          </dl>
        </dd>
        <dt><span class="chapter">2. <a href=
        "#RCL.INDEXING">Indexing</a></span></dt>
        <dd>
          <dl>
            <dt><span class="sect1">2.1. <a href=
            "#RCL.INDEXING.INTRODUCTION">Introduction</a></span></dt>
            <dd>
              <dl>
                <dt><span class="sect2">2.1.1. <a href=
                "#RCL.INDEXING.INTRODUCTION.MODES">Indexing
                modes</a></span></dt>
                <dt><span class="sect2">2.1.2. <a href=
                "#RCL.INDEXING.INTRODUCTION.CONFIG">Configurations,
                multiple indexes</a></span></dt>
                <dt><span class="sect2">2.1.3. <a href=
                "#idm227">Document types</a></span></dt>
                <dt><span class="sect2">2.1.4. <a href=
                "#idm268">Indexing failures</a></span></dt>
                <dt><span class="sect2">2.1.5. <a href=
                "#idm280">Recovery</a></span></dt>
              </dl>
            </dd>
            <dt><span class="sect1">2.2. <a href=
            "#RCL.INDEXING.STORAGE">Index storage</a></span></dt>
            <dd>
              <dl>
                <dt><span class="sect2">2.2.1. <a href=
                "#RCL.INDEXING.STORAGE.FORMAT"><span class=
                "application">Xapian</span> index
                formats</a></span></dt>
                <dt><span class="sect2">2.2.2. <a href=
                "#RCL.INDEXING.STORAGE.SECURITY">Security
                aspects</a></span></dt>
                <dt><span class="sect2">2.2.3. <a href=
                "#RCL.INDEXING.STORAGE.BIG">Special considerations
                for big indexes</a></span></dt>
              </dl>
            </dd>
            <dt><span class="sect1">2.3. <a href=
            "#RCL.INDEXING.CONFIG">Index
            configuration</a></span></dt>
            <dd>
              <dl>
                <dt><span class="sect2">2.3.1. <a href=
                "#RCL.INDEXING.CONFIG.MULTIPLE">Multiple
                indexes</a></span></dt>
                <dt><span class="sect2">2.3.2. <a href=
                "#RCL.INDEXING.CONFIG.SENS">Index case and
                diacritics sensitivity</a></span></dt>
                <dt><span class="sect2">2.3.3. <a href=
                "#RCL.INDEXING.CONFIG.THREADS">Indexing threads
                configuration</a></span></dt>
                <dt><span class="sect2">2.3.4. <a href=
                "#RCL.INDEXING.CONFIG.GUI">The index configuration
                GUI</a></span></dt>
              </dl>
            </dd>
            <dt><span class="sect1">2.4. <a href=
            "#RCL.INDEXING.WEBQUEUE">Indexing the WEB pages which
            you wisit.</a></span></dt>
            <dt><span class="sect1">2.5. <a href=
            "#RCL.INDEXING.EXTATTR">Extended attributes
            data</a></span></dt>
            <dt><span class="sect1">2.6. <a href=
            "#RCL.INDEXING.EXTTAGS">Importing external
            tags</a></span></dt>
            <dt><span class="sect1">2.7. <a href=
            "#RCL.INDEXING.PDF">The PDF input
            handler</a></span></dt>
            <dd>
              <dl>
                <dt><span class="sect2">2.7.1. <a href=
                "#RCL.INDEXING.PDF.OCR">OCR with
                Tesseract</a></span></dt>
                <dt><span class="sect2">2.7.2. <a href=
                "#RCL.INDEXING.PDF.XMP">XMP fields
                extraction</a></span></dt>
                <dt><span class="sect2">2.7.3. <a href=
                "#RCL.INDEXING.PDF.ATTACH">PDF attachment
                indexing</a></span></dt>
              </dl>
            </dd>
            <dt><span class="sect1">2.8. <a href=
            "#RCL.INDEXING.PERIODIC">Periodic
            indexing</a></span></dt>
            <dd>
              <dl>
                <dt><span class="sect2">2.8.1. <a href=
                "#RCL.INDEXING.PERIODIC.EXEC">Running
                indexing</a></span></dt>
                <dt><span class="sect2">2.8.2. <a href=
                "#RCL.INDEXING.PERIODIC.AUTOMAT">Using <span class=
                "command"><strong>cron</strong></span> to automate
                indexing</a></span></dt>
              </dl>
            </dd>
            <dt><span class="sect1">2.9. <a href=
            "#RCL.INDEXING.MONITOR">Real time
            indexing</a></span></dt>
            <dd>
              <dl>
                <dt><span class="sect2">2.9.1. <a href=
                "#RCL.INDEXING.MONITOR.START">Real time indexing:
                automatic daemon start</a></span></dt>
                <dt><span class="sect2">2.9.2. <a href=
                "#RCL.INDEXING.MONITOR.DETAILS">Real time indexing:
                miscellaneous details</a></span></dt>
              </dl>
            </dd>
          </dl>
        </dd>
        <dt><span class="chapter">3. <a href=
        "#RCL.SEARCH">Searching</a></span></dt>
        <dd>
          <dl>
            <dt><span class="sect1">3.1. <a href=
            "#RCL.SEARCH.GUI">Searching with the Qt graphical user
            interface</a></span></dt>
            <dd>
              <dl>
                <dt><span class="sect2">3.1.1. <a href=
                "#RCL.SEARCH.GUI.SIMPLE">Simple
                search</a></span></dt>
                <dt><span class="sect2">3.1.2. <a href=
                "#RCL.SEARCH.GUI.RESLIST">The default result
                list</a></span></dt>
                <dt><span class="sect2">3.1.3. <a href=
                "#RCL.SEARCH.GUI.RESTABLE">The result
                table</a></span></dt>
                <dt><span class="sect2">3.1.4. <a href=
                "#RCL.SEARCH.GUI.RUNSCRIPT">Running arbitrary
                commands on result files (1.20 and
                later)</a></span></dt>
                <dt><span class="sect2">3.1.5. <a href=
                "#RCL.SEARCH.GUI.THUMBNAILS">Displaying
                thumbnails</a></span></dt>
                <dt><span class="sect2">3.1.6. <a href=
                "#RCL.SEARCH.GUI.PREVIEW">The preview
                window</a></span></dt>
                <dt><span class="sect2">3.1.7. <a href=
                "#RCL.SEARCH.GUI.FRAGBUTS">The Query Fragments
                window</a></span></dt>
                <dt><span class="sect2">3.1.8. <a href=
                "#RCL.SEARCH.GUI.COMPLEX">Complex/advanced
                search</a></span></dt>
                <dt><span class="sect2">3.1.9. <a href=
                "#RCL.SEARCH.GUI.TERMEXPLORER">The term explorer
                tool</a></span></dt>
                <dt><span class="sect2">3.1.10. <a href=
                "#RCL.SEARCH.GUI.MULTIDB">Multiple
                indexes</a></span></dt>
                <dt><span class="sect2">3.1.11. <a href=
                "#RCL.SEARCH.GUI.HISTORY">Document
                history</a></span></dt>
                <dt><span class="sect2">3.1.12. <a href=
                "#RCL.SEARCH.GUI.SORT">Sorting search results and
                collapsing duplicates</a></span></dt>
                <dt><span class="sect2">3.1.13. <a href=
                "#RCL.SEARCH.GUI.TIPS">Search tips,
                shortcuts</a></span></dt>
                <dt><span class="sect2">3.1.14. <a href=
                "#RCL.SEARCH.SAVING">Saving and restoring queries
                (1.21 and later)</a></span></dt>
                <dt><span class="sect2">3.1.15. <a href=
                "#RCL.SEARCH.GUI.CUSTOM">Customizing the search
                interface</a></span></dt>
              </dl>
            </dd>
            <dt><span class="sect1">3.2. <a href=
            "#RCL.SEARCH.KIO">Searching with the KDE KIO
            slave</a></span></dt>
            <dd>
              <dl>
                <dt><span class="sect2">3.2.1. <a href=
                "#RCL.SEARCH.KIO.INTRO">What's this</a></span></dt>
                <dt><span class="sect2">3.2.2. <a href=
                "#RCL.SEARCH.KIO.SEARCHABLEDOCS">Searchable
                documents</a></span></dt>
              </dl>
            </dd>
            <dt><span class="sect1">3.3. <a href=
            "#RCL.SEARCH.COMMANDLINE">Searching on the command
            line</a></span></dt>
            <dt><span class="sect1">3.4. <a href=
            "#RCL.SEARCH.SYNONYMS">Using Synonyms
            (1.22)</a></span></dt>
            <dt><span class="sect1">3.5. <a href=
            "#RCL.SEARCH.PTRANS">Path translations</a></span></dt>
            <dt><span class="sect1">3.6. <a href=
            "#RCL.SEARCH.LANG">The query language</a></span></dt>
            <dd>
              <dl>
                <dt><span class="sect2">3.6.1. <a href=
                "#RCL.SEARCH.LANG.RANGES">Range
                clauses</a></span></dt>
                <dt><span class="sect2">3.6.2. <a href=
                "#RCL.SEARCH.LANG.MODIFIERS">Modifiers</a></span></dt>
              </dl>
            </dd>
            <dt><span class="sect1">3.7. <a href=
            "#RCL.SEARCH.CASEDIAC">Search case and diacritics
            sensitivity</a></span></dt>
            <dt><span class="sect1">3.8. <a href=
            "#RCL.SEARCH.ANCHORWILD">Anchored searches and
            wildcards</a></span></dt>
            <dd>
              <dl>
                <dt><span class="sect2">3.8.1. <a href=
                "#RCL.SEARCH.WILDCARDS">More about
                wildcards</a></span></dt>
                <dt><span class="sect2">3.8.2. <a href=
                "#RCL.SEARCH.ANCHOR">Anchored
                searches</a></span></dt>
              </dl>
            </dd>
            <dt><span class="sect1">3.9. <a href=
            "#RCL.SEARCH.DESKTOP">Desktop
            integration</a></span></dt>
            <dd>
              <dl>
                <dt><span class="sect2">3.9.1. <a href=
                "#RCL.SEARCH.SHORTCUT">Hotkeying
                recoll</a></span></dt>
                <dt><span class="sect2">3.9.2. <a href=
                "#RCL.KICKER-APPLET">The KDE Kicker Recoll
                applet</a></span></dt>
              </dl>
            </dd>
          </dl>
        </dd>
        <dt><span class="chapter">4. <a href=
        "#RCL.REMOVABLE">Removable volumes</a></span></dt>
        <dd>
          <dl>
            <dt><span class="sect1">4.1. <a href=
            "#RCL.REMOVABLE.MAIN">Indexing removable volumes in the
            main index</a></span></dt>
            <dt><span class="sect1">4.2. <a href=
            "#RCL.REMOVABLE.SELF">Self contained
            volumes</a></span></dt>
          </dl>
        </dd>
        <dt><span class="chapter">5. <a href=
        "#RCL.PROGRAM">Programming interface</a></span></dt>
        <dd>
          <dl>
            <dt><span class="sect1">5.1. <a href=
            "#RCL.PROGRAM.FILTERS">Writing a document input
            handler</a></span></dt>
            <dd>
              <dl>
                <dt><span class="sect2">5.1.1. <a href=
                "#RCL.PROGRAM.FILTERS.SIMPLE">Simple input
                handlers</a></span></dt>
                <dt><span class="sect2">5.1.2. <a href=
                "#RCL.PROGRAM.FILTERS.MULTIPLE">"Multiple"
                handlers</a></span></dt>
                <dt><span class="sect2">5.1.3. <a href=
                "#RCL.PROGRAM.FILTERS.ASSOCIATION">Telling
                <span class="application">Recoll</span> about the
                handler</a></span></dt>
                <dt><span class="sect2">5.1.4. <a href=
                "#RCL.PROGRAM.FILTERS.HTML">Input handler
                output</a></span></dt>
                <dt><span class="sect2">5.1.5. <a href=
                "#RCL.PROGRAM.FILTERS.PAGES">Page
                numbers</a></span></dt>
              </dl>
            </dd>
            <dt><span class="sect1">5.2. <a href=
            "#RCL.PROGRAM.FIELDS">Field data
            processing</a></span></dt>
            <dt><span class="sect1">5.3. <a href=
            "#RCL.PROGRAM.PYTHONAPI">Python API</a></span></dt>
            <dd>
              <dl>
                <dt><span class="sect2">5.3.1. <a href=
                "#RCL.PROGRAM.PYTHONAPI.INTRO">Introduction</a></span></dt>
                <dt><span class="sect2">5.3.2. <a href=
                "#RCL.PROGRAM.PYTHONAPI.ELEMENTS">Interface
                elements</a></span></dt>
                <dt><span class="sect2">5.3.3. <a href=
                "#RCL.PROGRAM.PYTHONAPI.SEARCH">Python search
                interface</a></span></dt>
                <dt><span class="sect2">5.3.4. <a href=
                "#RCL.PROGRAM.PYTHONAPI.UPDATE">Creating Python
                external indexers</a></span></dt>
                <dt><span class="sect2">5.3.5. <a href=
                "#RCL.PROGRAM.PYTHONAPI.COMPAT">Package
                compatibility with the previous
                version</a></span></dt>
              </dl>
            </dd>
          </dl>
        </dd>
        <dt><span class="chapter">6. <a href=
        "#RCL.INSTALL">Installation and
        configuration</a></span></dt>
        <dd>
          <dl>
            <dt><span class="sect1">6.1. <a href=
            "#RCL.INSTALL.BINARY">Installing a binary
            copy</a></span></dt>
            <dt><span class="sect1">6.2. <a href=
            "#RCL.INSTALL.EXTERNAL">Supporting
            packages</a></span></dt>
            <dt><span class="sect1">6.3. <a href=
            "#RCL.INSTALL.BUILDING">Building from
            source</a></span></dt>
            <dd>
              <dl>
                <dt><span class="sect2">6.3.1. <a href=
                "#RCL.INSTALL.BUILDING.PREREQS">Prerequisites</a></span></dt>
                <dt><span class="sect2">6.3.2. <a href=
                "#RCL.INSTALL.BUILDING.BUILDING">Building</a></span></dt>
                <dt><span class="sect2">6.3.3. <a href=
                "#RCL.INSTALL.BUILDING.INSTALL">Installing</a></span></dt>
                <dt><span class="sect2">6.3.4. <a href=
                "#RCL.INSTALL.BUILDING.PYTHON">Python API
                package</a></span></dt>
                <dt><span class="sect2">6.3.5. <a href=
                "#RCL.INSTALL.BUILDING.SOLARIS">Building on
                Solaris</a></span></dt>
              </dl>
            </dd>
            <dt><span class="sect1">6.4. <a href=
            "#RCL.INSTALL.CONFIG">Configuration
            overview</a></span></dt>
            <dd>
              <dl>
                <dt><span class="sect2">6.4.1. <a href=
                "#RCL.INSTALL.CONFIG.ENVIR">Environment
                variables</a></span></dt>
                <dt><span class="sect2">6.4.2. <a href=
                "#RCL.INSTALL.CONFIG.RECOLLCONF">Recoll main
                configuration file, recoll.conf</a></span></dt>
                <dt><span class="sect2">6.4.3. <a href=
                "#RCL.INSTALL.CONFIG.FIELDS">The fields
                file</a></span></dt>
                <dt><span class="sect2">6.4.4. <a href=
                "#RCL.INSTALL.CONFIG.MIMEMAP">The mimemap
                file</a></span></dt>
                <dt><span class="sect2">6.4.5. <a href=
                "#RCL.INSTALL.CONFIG.MIMECONF">The mimeconf
                file</a></span></dt>
                <dt><span class="sect2">6.4.6. <a href=
                "#RCL.INSTALL.CONFIG.MIMEVIEW">The mimeview
                file</a></span></dt>
                <dt><span class="sect2">6.4.7. <a href=
                "#RCL.INSTALL.CONFIG.PTRANS">The <code class=
                "filename">ptrans</code> file</a></span></dt>
                <dt><span class="sect2">6.4.8. <a href=
                "#RCL.INSTALL.CONFIG.EXAMPLES">Examples of
                configuration adjustments</a></span></dt>
              </dl>
            </dd>
          </dl>
        </dd>
      </dl>
    </div>
    <div class="chapter">
      <div class="titlepage">
        <div>
          <div>
            <h1 class="title"><a name="RCL.INTRODUCTION" id=
            "RCL.INTRODUCTION"></a>Chapter&nbsp;1.&nbsp;Introduction</h1>
          </div>
        </div>
      </div>
      <p>This document introduces full text search notions and
      describes the installation and use of the <span class=
      "application">Recoll</span> application. It is updated for
      <span class="application">Recoll</span> 1.25.</p>
      <p><span class="application">Recoll</span> was for a long
      time dedicated to Unix-like systems. It was only lately
      (2015) ported to <span class="application">MS-Windows</span>.
      Many references in this manual, especially file locations,
      are specific to Unix, and not valid on <span class=
      "application">Windows</span>, where some described features
      are also not available. The manual will be progressively
      updated. Until this happens, on <span class=
      "application">Windows</span>, most references to shared files
      can be translated by looking under the Recoll installation
      directory (esp. the <code class="filename">Share</code>
      subdirectory). The user configuration is stored by default
      under <code class="filename">AppData/Local/Recoll</code>
      inside the user directory, along with the index itself.</p>
      <div class="sect1">
        <div class="titlepage">
          <div>
            <div>
              <h2 class="title" style="clear: both"><a name=
              "RCL.INTRODUCTION.TRYIT" id=
              "RCL.INTRODUCTION.TRYIT"></a>1.1.&nbsp;Giving it a
              try</h2>
            </div>
          </div>
        </div>
        <p>If you do not like reading manuals (who does?) but wish
        to give <span class="application">Recoll</span> a try, just
        <a class="link" href="#RCL.INSTALL.BINARY" title=
        "6.1.&nbsp;Installing a binary copy">install</a> the
        application and start the <span class=
        "command"><strong>recoll</strong></span> graphical user
        interface (GUI), which will ask permission to index your
        home directory by default, allowing you to search
        immediately after indexing completes.</p>
        <p>Do not do this if your home directory contains a huge
        number of documents and you do not want to wait or are very
        short on disk space. In this case, you may first want to
        customize the <a class="link" href="#RCL.INDEXING.CONFIG"
        title="2.3.&nbsp;Index configuration">configuration</a> to
        restrict the indexed area (for the very impatient with a
        completed package install, from the <span class=
        "command"><strong>recoll</strong></span> GUI: <span class=
        "guimenu">Preferences</span> → <span class=
        "guimenuitem">Indexing configuration</span>, then adjust
        the <span class="guilabel">Top directories</span>
        section).</p>
        <p>On Unix/Linux, you may need to install the appropriate
        <a class="link" href="#RCL.INSTALL.EXTERNAL" title=
        "6.2.&nbsp;Supporting packages">supporting applications</a>
        for document types that need them (for example <span class=
        "application">antiword</span> for <span class=
        "application">Microsoft Word</span> files).</p>
        <p>The <span class="application">Recoll</span> for
        <span class="application">Windows</span> package is
        self-contained and includes most useful auxiliary programs.
        You will just need to install <span class=
        "application">Python</span> 2.7.</p>
      </div>
      <div class="sect1">
        <div class="titlepage">
          <div>
            <div>
              <h2 class="title" style="clear: both"><a name=
              "RCL.INTRODUCTION.SEARCH" id=
              "RCL.INTRODUCTION.SEARCH"></a>1.2.&nbsp;Full text
              search</h2>
            </div>
          </div>
        </div>
        <p><span class="application">Recoll</span> is a full text
        search application, which means that it finds your data by
        content rather than by external attributes (like the file
        name). You specify words (terms) which should or should not
        appear in the text you are looking for, and receive in
        return a list of matching documents, ordered so that the
        most <span class="emphasis"><em>relevant</em></span>
        documents will appear first.</p>
        <p>You do not need to remember in what file or email
        message you stored a given piece of information. You just
        ask for related terms, and the tool will return a list of
        documents where these terms are prominent, in a similar way
        to Internet search engines.</p>
        <p>Full text search applications try to determine which
        documents are most relevant to the search terms you
        provide. Computer algorithms for determining relevance can
        be very complex, and in general are inferior to the power
        of the human mind to rapidly determine relevance. The
        quality of relevance guessing is probably the most
        important aspect when evaluating a search application.
        <span class="application">Recoll</span> relies on the
        <span class="application">Xapian</span> probabilistic
        information retrieval library to determine relevance.</p>
        <p>In many cases, you are looking for all the forms of a
        word, including plurals, different tenses for a verb, or
        terms derived from the same root or <span class=
        "emphasis"><em>stem</em></span> (example: <em class=
        "replaceable"><code>floor, floors, floored,
        flooring...</code></em>). Queries are usually automatically
        expanded to all such related terms (words that reduce to
        the same stem). This can be prevented for searching for a
        specific form.</p>
        <p>Stemming, by itself, does not accommodate for
        misspellings or phonetic searches. A full text search
        application may also support this form of approximation.
        For example, a search for <em class=
        "replaceable"><code>aliterattion</code></em> returning no
        result might propose <em class=
        "replaceable"><code>alliteration, alteration, alterations,
        or altercation</code></em> as possible replacement terms.
        <span class="application">Recoll</span> bases its
        suggestions on the actual index contents, so that
        suggestions may be made for words which would not appear in
        a standard dictionary.</p>
      </div>
      <div class="sect1">
        <div class="titlepage">
          <div>
            <div>
              <h2 class="title" style="clear: both"><a name=
              "RCL.INTRODUCTION.RECOLL" id=
              "RCL.INTRODUCTION.RECOLL"></a>1.3.&nbsp;Recoll
              overview</h2>
            </div>
          </div>
        </div>
        <p><span class="application">Recoll</span> uses the
        <a class="ulink" href="http://www.xapian.org" target=
        "_top"><span class="application">Xapian</span></a>
        information retrieval library as its storage and retrieval
        engine. <span class="application">Xapian</span> is a very
        mature package using <a class="ulink" href=
        "http://www.xapian.org/docs/intro_ir.html" target="_top">a
        sophisticated probabilistic ranking model</a>.</p>
        <p>The <span class="application">Xapian</span> library
        manages an index database which describes where terms
        appear in your document files. It efficiently processes the
        complex queries which are produced by the <span class=
        "application">Recoll</span> query expansion mechanism, and
        is in charge of the all-important relevance computation
        task.</p>
        <p><span class="application">Recoll</span> provides the
        mechanisms and interface to get data into and out of the
        index. This includes translating the many possible document
        formats into pure text, handling term variations (using
        <span class="application">Xapian</span> stemmers), and
        spelling approximations (using the <span class=
        "application">aspell</span> speller), interpreting user
        queries and presenting results.</p>
        <p>In a shorter way, <span class=
        "application">Recoll</span> does the dirty footwork,
        <span class="application">Xapian</span> deals with the
        intelligent parts of the process.</p>
        <p>The <span class="application">Xapian</span> index can be
        big (roughly the size of the original document set), but it
        is not a document archive. <span class=
        "application">Recoll</span> can only display documents that
        still exist at the place from which they were indexed.
        (Actually, there is a way to reconstruct a document from
        the information in the index, but only the pure text is
        saved, possibly without punctuation and capitalization,
        depending on <span class="application">Recoll</span>
        version).</p>
        <p><span class="application">Recoll</span> stores all
        internal data in <span class="application">Unicode
        UTF-8</span> format, and it can index files of many types
        with different character sets, encodings, and languages
        into the same index. It can process documents embedded
        inside other documents (for example a pdf document stored
        inside a Zip archive sent as an email attachment...), down
        to an arbitrary depth.</p>
        <p>Stemming is the process by which <span class=
        "application">Recoll</span> reduces words to their radicals
        so that searching does not depend, for example, on a word
        being singular or plural (floor, floors), or on a verb
        tense (flooring, floored). Because the mechanisms used for
        stemming depend on the specific grammatical rules for each
        language, there is a separate <span class=
        "application">Xapian</span> stemmer module for most common
        languages where stemming makes sense.</p>
        <p><span class="application">Recoll</span> stores the
        unstemmed versions of terms in the main index and uses
        auxiliary databases for term expansion (one for each
        stemming language), which means that you can switch
        stemming languages between searches, or add a language
        without needing a full reindex.</p>
        <p>Storing documents written in different languages in the
        same index is possible, and commonly done. In this
        situation, you can specify several stemming languages for
        the index.</p>
        <p><span class="application">Recoll</span> currently makes
        no attempt at automatic language recognition, which means
        that the stemmer will sometimes be applied to terms from
        other languages with potentially strange results. In
        practise, even if this introduces possibilities of
        confusion, this approach has been proven quite useful, and
        it is much less cumbersome than separating your documents
        according to what language they are written in.</p>
        <p>By default, <span class="application">Recoll</span>
        strips most accents and diacritics from terms, and converts
        them to lower case before either storing them in the index
        or searching for them. As a consequence, it is impossible
        to search for a particular capitalization of a term
        (<code class="literal">US</code> / <code class=
        "literal">us</code>), or to discriminate two terms based on
        diacritics (<code class="literal">sake</code> /
        <code class="literal">saké</code>, <code class=
        "literal">mate</code> / <code class=
        "literal">maté</code>).</p>
        <p><span class="application">Recoll</span> can optionally
        store the raw terms, without accent stripping or case
        conversion. In this configuration, default searches will
        behave as before, but it is possible to perform searches
        sensitive to case and diacritics. This is described in more
        detail in the <a class="link" href=
        "#RCL.INDEXING.CONFIG.SENS" title=
        "2.3.2.&nbsp;Index case and diacritics sensitivity">section
        about index case and diacritics sensitivity</a>.</p>
        <p><span class="application">Recoll</span> has many
        parameters which define exactly what to index, and how to
        classify and decode the source documents. These are kept in
        <a class="link" href="#RCL.INDEXING.CONFIG" title=
        "2.3.&nbsp;Index configuration">configuration files</a>. A
        default configuration is copied into a standard location
        (usually something like <code class=
        "filename">/usr/share/recoll/examples</code>) during
        installation. The default values set by the configuration
        files in this directory may be overridden by values set
        inside your personal configuration, found by default in the
        <code class="filename">.recoll</code> sub-directory of your
        home directory. The default configuration will index your
        home directory with default parameters and should be
        sufficient for giving <span class=
        "application">Recoll</span> a try, but you may want to
        adjust it later, which can be done either by editing the
        text files or by using configuration menus in the
        <span class="command"><strong>recoll</strong></span> GUI.
        Some other parameters affecting only the <span class=
        "command"><strong>recoll</strong></span> GUI are stored in
        the standard location defined by <span class=
        "application">Qt</span>.</p>
        <p>The <a class="link" href="#RCL.INDEXING.PERIODIC.EXEC"
        title="2.8.1.&nbsp;Running indexing">indexing process</a>
        is started automatically (after asking permission), the
        first time you execute the <span class=
        "command"><strong>recoll</strong></span> GUI. Indexing can
        also be performed by executing the <span class=
        "command"><strong>recollindex</strong></span> command.
        <span class="application">Recoll</span> indexing is
        multithreaded by default when appropriate hardware
        resources are available, and can perform in parallel
        multiple tasks for text extraction, segmentation and index
        updates.</p>
        <p><a class="link" href="#RCL.SEARCH" title=
        "Chapter&nbsp;3.&nbsp;Searching">Searches</a> are usually
        performed inside the <span class=
        "command"><strong>recoll</strong></span> GUI, which has
        many options to help you find what you are looking for.
        However, there are other ways to perform <span class=
        "application">Recoll</span> searches:</p>
        <div class="itemizedlist">
          <ul class="itemizedlist" style="list-style-type: disc;">
            <li class="listitem">
              <p>A <a class="link" href="#RCL.SEARCH.COMMANDLINE"
              title=
              "3.3.&nbsp;Searching on the command line">command
              line interface</a>.</p>
            </li>
            <li class="listitem">
              <p>A <a class="link" href="#RCL.PROGRAM.PYTHONAPI"
              title="5.3.&nbsp;Python API"><span class=
              "application">Python</span> programming
              interface</a></p>
            </li>
            <li class="listitem">
              <p>A <a class="link" href="#RCL.SEARCH.KIO" title=
              "3.2.&nbsp;Searching with the KDE KIO slave"><span class="application">
              KDE</span> KIO slave module</a>.</p>
            </li>
            <li class="listitem">
              <p>A Ubuntu Unity <a class="ulink" href=
              "https://www.lesbonscomptes.com/recoll/download.html"
              target="_top">Scope</a> module.</p>
            </li>
            <li class="listitem">
              <p>A Gnome Shell <a class="ulink" href=
              "https://www.lesbonscomptes.com/recoll/download.html"
              target="_top">Search Provider</a>.</p>
            </li>
            <li class="listitem">
              <p>A <a class="ulink" href=
              "https://github.com/koniu/recoll-webui" target=
              "_top">WEB interface</a>.</p>
            </li>
          </ul>
        </div>
      </div>
    </div>
    <div class="chapter">
      <div class="titlepage">
        <div>
          <div>
            <h1 class="title"><a name="RCL.INDEXING" id=
            "RCL.INDEXING"></a>Chapter&nbsp;2.&nbsp;Indexing</h1>
          </div>
        </div>
      </div>
      <div class="sect1">
        <div class="titlepage">
          <div>
            <div>
              <h2 class="title" style="clear: both"><a name=
              "RCL.INDEXING.INTRODUCTION" id=
              "RCL.INDEXING.INTRODUCTION"></a>2.1.&nbsp;Introduction</h2>
            </div>
          </div>
        </div>
        <p>Indexing is the process by which the set of documents is
        analyzed and the data entered into the database.
        <span class="application">Recoll</span> indexing is
        normally incremental: documents will only be processed if
        they have been modified since the last run. On the first
        execution, all documents will need processing. A full index
        build can be forced later by specifying an option to the
        indexing command (<span class=
        "command"><strong>recollindex</strong></span> <code class=
        "option">-z</code> or <code class="option">-Z</code>).</p>
        <p><span class=
        "command"><strong>recollindex</strong></span> skips files
        which caused an error during a previous pass. This is a
        performance optimization, and a new behaviour in version
        1.21 (failed files were always retried by previous
        versions). The command line option <code class=
        "option">-k</code> can be set to retry failed files, for
        example after updating an input handler.</p>
        <p>The following sections give an overview of different
        aspects of the indexing processes and configuration, with
        links to detailed sections.</p>
        <p>Depending on your data, temporary files may be needed
        during indexing, some of them possibly quite big. You can
        use the <code class="envar">RECOLL_TMPDIR</code> or
        <code class="envar">TMPDIR</code> environment variables to
        determine where they are created (the default is to use
        <code class="filename">/tmp</code>). Using <code class=
        "envar">TMPDIR</code> has the nice property that it may
        also be taken into account by auxiliary commands executed
        by <span class=
        "command"><strong>recollindex</strong></span>.</p>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name=
                "RCL.INDEXING.INTRODUCTION.MODES" id=
                "RCL.INDEXING.INTRODUCTION.MODES"></a>2.1.1.&nbsp;Indexing
                modes</h3>
              </div>
            </div>
          </div>
          <p><span class="application">Recoll</span> indexing can
          be performed along two main modes:</p>
          <div class="itemizedlist">
            <ul class="itemizedlist" style=
            "list-style-type: disc;">
              <li class="listitem">
                <p><b><a class="link" href="#RCL.INDEXING.PERIODIC"
                title="2.8.&nbsp;Periodic indexing">Periodic (or
                batch) indexing:</a>&nbsp;</b><span class=
                "command"><strong>recollindex</strong></span> is
                executed at discrete times. The typical usage is to
                have a nightly run <a class="link" href=
                "#RCL.INDEXING.PERIODIC.AUTOMAT" title=
                "2.8.2.&nbsp;Using cron to automate indexing">programmed</a>
                into your <span class=
                "command"><strong>cron</strong></span> file.</p>
              </li>
              <li class="listitem">
                <p><b><a class="link" href="#RCL.INDEXING.MONITOR"
                title="2.9.&nbsp;Real time indexing">Real time
                indexing:</a>&nbsp;</b><span class=
                "command"><strong>recollindex</strong></span> runs
                permanently as a daemon and uses a file system
                alteration monitor (e.g. <span class=
                "application">inotify</span>) to detect file
                changes. New or updated files are indexed at
                once.</p>
              </li>
            </ul>
          </div>
          <p>The choice between the two methods is mostly a matter
          of preference, and they can be combined by setting up
          multiple indexes (ie: use periodic indexing on a big
          documentation directory, and real time indexing on a
          small home directory). Monitoring a big file system tree
          can consume significant system resources.</p>
          <p>With <span class="application">Recoll</span> 1.24 and
          newer, it is also possible to set up an index so that
          only a subset of the tree will be monitored and the rest
          will be covered by batch/incremental indexing. (See the
          details in the <a class="link" href=
          "#RCL.INDEXING.MONITOR" title=
          "2.9.&nbsp;Real time indexing">Real time indexing</a>
          section.</p>
          <p>The choice of method and the parameters used can be
          configured from the <span class=
          "command"><strong>recoll</strong></span> GUI:
          <span class="guimenu">Preferences</span> → <span class=
          "guimenuitem">Indexing schedule</span></p>
          <p>The GUI <span class="guimenu">File</span> menu also
          has entries to start or stop the current indexing
          operation. Stopping indexing is performed by killing the
          <span class="command"><strong>recollindex</strong></span>
          process, which will checkpoint its state and exit. A
          later restart of indexing will mostly resume from where
          things stopped (the file tree walk has to be restarted
          from the beginning).</p>
          <p>When the real time indexer is running, two operations
          are available from the menu: 'Stop' and 'Trigger
          incremental pass'. When no indexing is running, you have
          a choice of updating the index or rebuilding it (the
          first choice only processes changed files, the second one
          zeroes the index before starting so that all files are
          processed).</p>
        </div>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name=
                "RCL.INDEXING.INTRODUCTION.CONFIG" id=
                "RCL.INDEXING.INTRODUCTION.CONFIG"></a>2.1.2.&nbsp;Configurations,
                multiple indexes</h3>
              </div>
            </div>
          </div>
          <p><span class="application">Recoll</span> supports
          defining multiple indexes.</p>
          <p>Each index is defined by its own <a class="link" href=
          "#RCL.INDEXING.CONFIG" title=
          "2.3.&nbsp;Index configuration">configuration
          directory</a>, in which several configuration files
          describe what should be indexed and how.</p>
          <p>A default personal configuration directory
          (<code class="filename">$HOME/.recoll/</code>) is created
          when a <span class="application">Recoll</span> program is
          first executed. This configuration is the one used for
          indexing and querying when no specific configuration is
          specified.</p>
          <p>All configuration parameters have defaults, defined in
          system-wide files. Without further customisation, the
          default configuration will process your complete home
          directory, with a reasonable set of defaults. It can be
          changed to process a different area of the file system,
          select files in different ways, and many other
          things.</p>
          <p>In some cases, it may be interesting, for example, to
          index different areas of the file system into separate
          indexes, or use different options. You can do this by
          creating additional configuration directories.</p>
          <p>Examples of usage would be to separate personal and
          shared indexes, or to take advantage of the organization
          of your data to improve search precision.</p>
          <p>A specific configuration can be selected by setting
          the <code class="envar">RECOLL_CONFDIR</code> environment
          variable, or giving the <code class="option">-c</code>
          option to any of the <span class=
          "application">Recoll</span> commands.</p>
          <p>When generating indexes, the different configurations
          are entirely independant (no parameters are ever shared
          between configurations when indexing).</p>
          <p>Multiple indexes can be queryied concurrently, either
          from the GUI or the command line. When doing this, there
          is always a main configuration, from which both
          configuration and index data are used. Only the index
          data from the additional indexes is used (their
          configuration parameters are ignored).</p>
          <p>This is important and sometimes confusing, so it will
          be rephrased here: for index generation, multiple
          configurations are totally independant from each other.
          When querying, configuration and data are used from the
          main index (the one designated by <code class=
          "literal">-c</code> or <code class=
          "envar">RECOLL_CONFDIR</code>), and only the data from
          the additional indexes is used. This also implies that
          <a class="link" href="#RCL.INDEXING.CONFIG.MULTIPLE"
          title="2.3.1.&nbsp;Multiple indexes">some parameters
          should be consistent among the configurations</a> for
          indexes which are to be used together.</p>
        </div>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name="idm227" id=
                "idm227"></a>2.1.3.&nbsp;Document types</h3>
              </div>
            </div>
          </div>
          <p><span class="application">Recoll</span> knows about
          quite a few different document types. The parameters for
          document types recognition and processing are set in
          <a class="link" href="#RCL.INDEXING.CONFIG" title=
          "2.3.&nbsp;Index configuration">configuration
          files</a>.</p>
          <p>Most file types, like HTML or word processing files,
          only hold one document. Some file types, like email
          folders or zip archives, can hold many individually
          indexed documents, which may themselves be compound ones.
          Such hierarchies can go quite deep, and <span class=
          "application">Recoll</span> can process, for example, a
          <span class="application">LibreOffice</span> document
          stored as an attachment to an email message inside an
          email folder archived in a zip file...</p>
          <p><span class=
          "command"><strong>recollindex</strong></span> processes
          plain text, HTML, OpenDocument (Open/LibreOffice), email
          formats, and a few others internally.</p>
          <p>Other file types (ie: postscript, pdf, ms-word, rtf
          ...) need external applications for preprocessing. The
          list is in the <a class="link" href=
          "#RCL.INSTALL.EXTERNAL" title=
          "6.2.&nbsp;Supporting packages">installation</a> section.
          After every indexing operation, <span class=
          "application">Recoll</span> updates a list of commands
          that would be needed for indexing existing files types.
          This list can be displayed by selecting the menu option
          <span class="guimenu">File</span> → <span class=
          "guimenuitem">Show Missing Helpers</span> in the
          <span class="command"><strong>recoll</strong></span> GUI.
          It is stored in the <code class="filename">missing</code>
          text file inside the configuration directory.</p>
          <p>By default, <span class="application">Recoll</span>
          will try to index any file type that it has a way to
          read. This is sometimes not desirable, and there are ways
          to either exclude some types, or on the contrary define a
          positive list of types to be indexed. In the latter case,
          any type not in the list will be ignored.</p>
          <p>Excluding files by name can be done by adding wildcard
          name patterns to the <a class="link" href=
          "#RCL.INSTALL.CONFIG.RECOLLCONF.SKIPPEDNAMES">skippedNames</a>
          list, which can be done from the GUI Index configuration
          menu. Excluding by type can be done by setting the
          <a class="link" href=
          "#RCL.INSTALL.CONFIG.RECOLLCONF.EXCLUDEDMIMETYPES">excludedmimetypes</a>
          list in the configuration file (1.20 and later). This can
          be redefined for subdirectories.</p>
          <p>You can also define an exclusive list of MIME types to
          be indexed (no others will be indexed), by settting the
          <a class="link" href=
          "#RCL.INSTALL.CONFIG.RECOLLCONF.INDEXEDMIMETYPES">indexedmimetypes</a>
          configuration variable. Example:</p>
          <pre class="programlisting">
        indexedmimetypes = text/html application/pdf
      </pre>
          <p>It is possible to redefine this parameter for
          subdirectories. Example:</p>
          <pre class="programlisting">
      [/path/to/my/dir]
      indexedmimetypes = application/pdf
    </pre>
          <p>(When using sections like this, don't forget that they
          remain in effect until the end of the file or another
          section indicator).</p>
          <p><code class="literal">excludedmimetypes</code> or
          <code class="literal">indexedmimetypes</code>, can be set
          either by editing the <a class="link" href=
          "#RCL.INSTALL.CONFIG.RECOLLCONF" title=
          "6.4.2.&nbsp;Recoll main configuration file, recoll.conf">
          configuration file (<code class=
          "filename">recoll.conf</code>)</a> for the index, or by
          using the GUI index configuration tool.</p>
          <div class="note" style=
          "margin-left: 0.5in; margin-right: 0.5in;">
            <h3 class="title">Note about MIME types</h3>
            <p>When editing the <code class=
            "literal">indexedmimetypes</code> or <code class=
            "literal">excludedmimetypes</code> lists, you should
            use the MIME values listed in the <code class=
            "filename">mimemap</code> file or in Recoll result
            lists in preference to <code class="literal">file
            -i</code> output: there are a number of differences.
            The <code class="literal">file -i</code> output should
            only be used for files without extensions, or for which
            the extension is not listed in <code class=
            "filename">mimemap</code></p>
          </div>
        </div>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name="idm268" id=
                "idm268"></a>2.1.4.&nbsp;Indexing failures</h3>
              </div>
            </div>
          </div>
          <p>Indexing may fail for some documents, for a number of
          reasons: a helper program may be missing, the document
          may be corrupt, we may fail to uncompress a file because
          no file system space is available, etc.</p>
          <p><span class="application">Recoll</span> versions prior
          to 1.21 always retried to index files which had
          previously caused an error. This guaranteed that anything
          that may have become indexable (for example because a
          helper had been installed) would be indexed. However this
          was bad for performance because some indexing failures
          may be quite costly (for example failing to uncompress a
          big file because of insufficient disk space).</p>
          <p>The indexer in <span class="application">Recoll</span>
          versions 1.21 and later does not retry failed files by
          default. Retrying will only occur if an explicit option
          (<code class="option">-k</code>) is set on the
          <span class="command"><strong>recollindex</strong></span>
          command line, or if a script executed when <span class=
          "command"><strong>recollindex</strong></span> starts up
          says so. The script is defined by a configuration
          variable (<code class=
          "literal">checkneedretryindexscript</code>), and makes a
          rather lame attempt at deciding if a helper command may
          have been installed, by checking if any of the common
          <code class="filename">bin</code> directories have
          changed.</p>
        </div>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name="idm280" id=
                "idm280"></a>2.1.5.&nbsp;Recovery</h3>
              </div>
            </div>
          </div>
          <p>In the rare case where the index becomes corrupted
          (which can signal itself by weird search results or
          crashes), the index files need to be erased before
          restarting a clean indexing pass. Just delete the
          <code class="filename">xapiandb</code> directory (see
          <a class="link" href="#RCL.INDEXING.STORAGE" title=
          "2.2.&nbsp;Index storage">next section</a>), or,
          alternatively, start the next <span class=
          "command"><strong>recollindex</strong></span> with the
          <code class="option">-z</code> option, which will reset
          the database before indexing. The difference between the
          two methods is that the second will not change the
          current index format, which may be undesirable if a newer
          format is supported by the <span class=
          "application">Xapian</span> version.</p>
        </div>
      </div>
      <div class="sect1">
        <div class="titlepage">
          <div>
            <div>
              <h2 class="title" style="clear: both"><a name=
              "RCL.INDEXING.STORAGE" id=
              "RCL.INDEXING.STORAGE"></a>2.2.&nbsp;Index
              storage</h2>
            </div>
          </div>
        </div>
        <p>The default location for the index data is the
        <code class="filename">xapiandb</code> subdirectory of the
        <span class="application">Recoll</span> configuration
        directory, typically <code class=
        "filename">$HOME/.recoll/xapiandb/</code>. This can be
        changed via two different methods (with different
        purposes):</p>
        <div class="orderedlist">
          <ol class="orderedlist" type="1">
            <li class="listitem">
              <p>For a given configuration directory, you can
              specify a non-default storage location for the index
              by setting the <code class="varname">dbdir</code>
              parameter in the configuration file (see the
              <a class="link" href="#RCL.INSTALL.CONFIG.RECOLLCONF"
              title=
              "6.4.2.&nbsp;Recoll main configuration file, recoll.conf">
              configuration section</a>). This method would mainly
              be of use if you wanted to keep the configuration
              directory in its default location, but desired
              another location for the index, typically out of disk
              occupation or performance concerns.</p>
            </li>
            <li class="listitem">
              <p>You can specify a different configuration
              directory by setting the <code class=
              "envar">RECOLL_CONFDIR</code> environment variable,
              or using the <code class="option">-c</code> option to
              the <span class="application">Recoll</span> commands.
              This method would typically be used to index
              different areas of the file system to different
              indexes. For example, if you were to issue the
              following command:</p>
              <pre class="programlisting">
              recoll -c ~/.indexes-email</pre>
              <p>Then <span class="application">Recoll</span> would
              use configuration files stored in <code class=
              "filename">~/.indexes-email/</code> and, (unless
              specified otherwise in <code class=
              "filename">recoll.conf</code>) would look for the
              index in <code class=
              "filename">~/.indexes-email/xapiandb/</code>.</p>
              <p>Using multiple configuration directories and
              <a class="link" href="#RCL.INSTALL.CONFIG.RECOLLCONF"
              title=
              "6.4.2.&nbsp;Recoll main configuration file, recoll.conf">
              configuration options</a> allows you to tailor
              multiple configurations and indexes to handle
              whatever subset of the available data you wish to
              make searchable.</p>
            </li>
          </ol>
        </div>
        <p>The size of the index is determined by the size of the
        set of documents, but the ratio can vary a lot. For a
        typical mixed set of documents, the index size will often
        be close to the data set size. In specific cases (a set of
        compressed mbox files for example), the index can become
        much bigger than the documents. It may also be much smaller
        if the documents contain a lot of images or other
        non-indexed data (an extreme example being a set of mp3
        files where only the tags would be indexed).</p>
        <p>Of course, images, sound and video do not increase the
        index size, which means that in most cases, the space used
        by the index will be negligible against the total amount of
        data on the computer.</p>
        <p>The index data directory (<code class=
        "filename">xapiandb</code>) only contains data that can be
        completely rebuilt by an index run (as long as the original
        documents exist), and it can always be destroyed
        safely.</p>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name=
                "RCL.INDEXING.STORAGE.FORMAT" id=
                "RCL.INDEXING.STORAGE.FORMAT"></a>2.2.1.&nbsp;<span class="application">Xapian</span>
                index formats</h3>
              </div>
            </div>
          </div>
          <p><span class="application">Xapian</span> versions
          usually support several formats for index storage. A
          given major <span class="application">Xapian</span>
          version will have a current format, used to create new
          indexes, and will also support the format from the
          previous major version.</p>
          <p><span class="application">Xapian</span> will not
          convert automatically an existing index from the older
          format to the newer one. If you want to upgrade to the
          new format, or if a very old index needs to be converted
          because its format is not supported any more, you will
          have to explicitly delete the old index (typically
          <code class="filename">~/.recoll/xapiandb</code>), then
          run a normal indexing command. Using <span class=
          "command"><strong>recollindex</strong></span> option
          <code class="option">-z</code> would not work in this
          situation.</p>
        </div>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name=
                "RCL.INDEXING.STORAGE.SECURITY" id=
                "RCL.INDEXING.STORAGE.SECURITY"></a>2.2.2.&nbsp;Security
                aspects</h3>
              </div>
            </div>
          </div>
          <p>The <span class="application">Recoll</span> index does
          not hold complete copies of the indexed documents (it
          almost does after version 1.24). But it does hold enough
          data to allow for an almost complete reconstruction. If
          confidential data is indexed, access to the database
          directory should be restricted.</p>
          <p><span class="application">Recoll</span> will create
          the configuration directory with a mode of 0700 (access
          by owner only). As the index data directory is by default
          a sub-directory of the configuration directory, this
          should result in appropriate protection.</p>
          <p>If you use another setup, you should think of the kind
          of protection you need for your index, set the directory
          and files access modes appropriately, and also maybe
          adjust the <code class="literal">umask</code> used during
          index updates.</p>
        </div>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name=
                "RCL.INDEXING.STORAGE.BIG" id=
                "RCL.INDEXING.STORAGE.BIG"></a>2.2.3.&nbsp;Special
                considerations for big indexes</h3>
              </div>
            </div>
          </div>
          <p>This only needs concern you if your index is going to
          be bigger than around 5 GBytes. Beyond 10 GBytes, it
          becomes a serious issue. Most people have much smaller
          indexes. For reference, 5 GBytes would be around 2000
          bibles, a lot of text. If you have a huge text dataset
          (remember: images don't count, the text content of PDFs
          is typically less than 5% of the file size), read on.</p>
          <p>The amount of writing performed by Xapian during index
          creation is not linear with the index size (it is
          somewhere between linear and quadratic). For big indexes
          this becomes a performance issue, and may even be an SSD
          disk wear issue.</p>
          <p>The problem can be mitigated by observing the
          following rules:</p>
          <div class="itemizedlist">
            <ul class="itemizedlist" style=
            "list-style-type: disc;">
              <li class="listitem">
                <p>Partition the data set and create several
                indexes of reasonable size rather than a huge one.
                These indexes can then be queried in parallel
                (using the <span class="application">Recoll</span>
                external indexes facility), or merged using
                <span class=
                "command"><strong>xapian-compact</strong></span>.</p>
              </li>
              <li class="listitem">
                <p>Have a lot of RAM available and set the
                <code class="literal">idxflushmb</code>
                <span class="application">Recoll</span>
                configuration parameter as high as you can without
                swapping (experimentation will be needed). 200
                would be a minimum in this context.</p>
              </li>
              <li class="listitem">
                <p>Use Xapian 1.4.10 or newer, as this version
                brought a significant improvement in the amount of
                writes.</p>
              </li>
            </ul>
          </div>
        </div>
      </div>
      <div class="sect1">
        <div class="titlepage">
          <div>
            <div>
              <h2 class="title" style="clear: both"><a name=
              "RCL.INDEXING.CONFIG" id=
              "RCL.INDEXING.CONFIG"></a>2.3.&nbsp;Index
              configuration</h2>
            </div>
          </div>
        </div>
        <p>Variables set inside the <a class="link" href=
        "#RCL.INSTALL.CONFIG" title=
        "6.4.&nbsp;Configuration overview"><span class=
        "application">Recoll</span> configuration files</a> control
        which areas of the file system are indexed, and how files
        are processed. These variables can be set either by editing
        the text files or by using the <a class="link" href=
        "#RCL.INDEXING.CONFIG.GUI" title=
        "2.3.4.&nbsp;The index configuration GUI">dialogs in the
        <span class="command"><strong>recoll</strong></span>
        GUI</a>.</p>
        <p>The first time you start <span class=
        "command"><strong>recoll</strong></span>, you will be asked
        whether or not you would like it to build the index. If you
        want to adjust the configuration before indexing, just
        click <span class="guilabel">Cancel</span> at this point,
        which will get you into the configuration interface. If you
        exit at this point, <code class="filename">recoll</code>
        will have created a <code class="filename">~/.recoll</code>
        directory containing empty configuration files, which you
        can edit by hand.</p>
        <p>The configuration is documented inside the <a class=
        "link" href="#RCL.INSTALL.CONFIG" title=
        "6.4.&nbsp;Configuration overview">installation chapter</a>
        of this document, or in the <span class=
        "citerefentry"><span class=
        "refentrytitle">recoll.conf</span>(5)</span> man page, but
        the most current information will most likely be the
        comments inside the sample file. The most immediately
        useful variable is probably <a class="link" href=
        "#RCL.INSTALL.CONFIG.RECOLLCONF.TOPDIRS"><code class=
        "varname">topdirs</code></a>, which determines what
        subtrees and files get indexed.</p>
        <p>The applications needed to index file types other than
        text, HTML or email (ie: pdf, postscript, ms-word...) are
        described in the <a class="link" href=
        "#RCL.INSTALL.EXTERNAL" title=
        "6.2.&nbsp;Supporting packages">external packages
        section.</a></p>
        <p>As of Recoll 1.18 there are two incompatible types of
        Recoll indexes, depending on the treatment of character
        case and diacritics. A <a class="link" href=
        "#RCL.INDEXING.CONFIG.SENS" title=
        "2.3.2.&nbsp;Index case and diacritics sensitivity">further
        section</a> describes the two types in more detail.</p>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name=
                "RCL.INDEXING.CONFIG.MULTIPLE" id=
                "RCL.INDEXING.CONFIG.MULTIPLE"></a>2.3.1.&nbsp;Multiple
                indexes</h3>
              </div>
            </div>
          </div>
          <p>Multiple <span class="application">Recoll</span>
          indexes can be created by using several configuration
          directories which are typically set to index different
          areas of the file system. A specific index can be
          selected for updating or searching, using the
          <code class="envar">RECOLL_CONFDIR</code> environment
          variable or the <code class="option">-c</code> option to
          <span class="command"><strong>recoll</strong></span> and
          <span class=
          "command"><strong>recollindex</strong></span>.</p>
          <p>When working with the <span class=
          "command"><strong>recoll</strong></span> index
          configuration GUI, the configuration directory for which
          parameters are modified is the one which was selected by
          <code class="envar">RECOLL_CONFDIR</code> or the
          <code class="option">-c</code> parameter, and there is no
          way to switch configurations within the GUI.</p>
          <p>Additional configuration directories (beyond
          <code class="filename">~/.recoll</code>) must be created
          by hand (<span class=
          "command"><strong>mkdir</strong></span> or such), the GUI
          will not do it. This is to avoid mistakenly creating
          additional directories when an argument is mistyped.</p>
          <p>A typical usage scenario for the multiple index
          feature would be for a system administrator to set up a
          central index for shared data, that you choose to search
          or not in addition to your personal data. Of course,
          there are other possibilities. There are many cases where
          you know the subset of files that should be searched, and
          where narrowing the search can improve the results. You
          can achieve approximately the same effect with the
          directory filter in advanced search, but multiple indexes
          will have better performance and may be worth the
          trouble.</p>
          <p>A <span class=
          "command"><strong>recollindex</strong></span> program
          instance can only update one specific index, and it will
          only use parameters from a single configuration (no
          parameters are ever shared between configurations when
          indexing).</p>
          <p>Multiple indexes can be queryied concurrently, either
          from the GUI or the command line. When doing this, there
          is always a main configuration, from which both
          configuration and index data are used. Only the index
          data from the additional indexes is used (their
          configuration parameters are ignored).</p>
          <p>When searching, the current main index (defined by
          <code class="envar">RECOLL_CONFDIR</code> or <code class=
          "option">-c</code>) is always active. If this is
          undesirable, you can set up your base configuration to
          index an empty directory.</p>
          <p>If a set of multiple indexes are to be used together
          for searches, some configuration parameters must be
          consistent among the set. These are parameters which need
          to be the same when indexing and searching. As the
          parameters come from the main configuration when
          searching, they need to be compatible with what was set
          when creating the other indexes (which came from their
          respective configuration directories).</p>
          <p>Most importantly, all indexes to be queried
          concurrently must have the same option concerning
          character case and diacritics stripping, but there are
          other constraints. Most of the relevant parameters are
          described in the <a class="link" href=
          "#RCL.INSTALL.CONFIG.RECOLLCONF.TERMS" title=
          "6.4.2.2.&nbsp;Parameters affecting how we generate terms and organize the index">
          linked section</a>.</p>
          <p>The different search interfaces (GUI, command line,
          ...) have different methods to define the set of indexes
          to be used, see the appropriate section.</p>
        </div>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name=
                "RCL.INDEXING.CONFIG.SENS" id=
                "RCL.INDEXING.CONFIG.SENS"></a>2.3.2.&nbsp;Index
                case and diacritics sensitivity</h3>
              </div>
            </div>
          </div>
          <p>As of <span class="application">Recoll</span> version
          1.18 you have a choice of building an index with terms
          stripped of character case and diacritics, or one with
          raw terms. For a source term of <code class=
          "literal">Résumé</code>, the former will store
          <code class="literal">resume</code>, the latter
          <code class="literal">Résumé</code>.</p>
          <p>Each type of index allows performing searches
          insensitive to case and diacritics: with a raw index, the
          user entry will be expanded to match all case and
          diacritics variations present in the index. With a
          stripped index, the search term will be stripped before
          searching.</p>
          <p>A raw index allows for another possibility which a
          stripped index cannot offer: using case and diacritics to
          discriminate between terms, returning different results
          when searching for <code class="literal">US</code> and
          <code class="literal">us</code> or <code class=
          "literal">resume</code> and <code class=
          "literal">résumé</code>. Read the <a class="link" href=
          "#RCL.SEARCH.CASEDIAC" title=
          "3.7.&nbsp;Search case and diacritics sensitivity">section
          about search case and diacritics sensitivity</a> for more
          details.</p>
          <p>The type of index to be created is controlled by the
          <code class="literal">indexStripChars</code>
          configuration variable which can only be changed by
          editing the configuration file. Any change implies an
          index reset (not automated by <span class=
          "application">Recoll</span>), and all indexes in a search
          must be set in the same way (again, not checked by
          <span class="application">Recoll</span>).</p>
          <p>If the <code class="literal">indexStripChars</code> is
          not set, <span class="application">Recoll</span> 1.18
          creates a stripped index by default, for compatibility
          with previous versions.</p>
          <p>As a cost for added capability, a raw index will be
          slightly bigger than a stripped one (around 10%). Also,
          searches will be more complex, so probably slightly
          slower, and the feature is still young, so that a certain
          amount of weirdness cannot be excluded.</p>
          <p>One of the most adverse consequence of using a raw
          index is that some phrase and proximity searches may
          become impossible: because each term needs to be
          expanded, and all combinations searched for, the
          multiplicative expansion may become unmanageable.</p>
        </div>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name=
                "RCL.INDEXING.CONFIG.THREADS" id=
                "RCL.INDEXING.CONFIG.THREADS"></a>2.3.3.&nbsp;Indexing
                threads configuration</h3>
              </div>
            </div>
          </div>
          <p>The <span class="application">Recoll</span> indexing
          process <span class=
          "command"><strong>recollindex</strong></span> can use
          multiple threads to speed up indexing on multiprocessor
          systems. The work done to index files is divided in
          several stages and some of the stages can be executed by
          multiple threads. The stages are:</p>
          <div class="orderedlist">
            <ol class="orderedlist" type="1">
              <li class="listitem">
                <p>File system walking: this is always performed by
                the main thread.</p>
              </li>
              <li class="listitem">
                <p>File conversion and data extraction.</p>
              </li>
              <li class="listitem">
                <p>Text processing (splitting, stemming, etc.).</p>
              </li>
              <li class="listitem">
                <p><span class="application">Xapian</span> index
                update.</p>
              </li>
            </ol>
          </div>
          <p>You can also read a <a class="ulink" href=
          "http://www.recoll.org/idxthreads/threadingRecoll.html"
          target="_top">longer document</a> about the
          transformation of <span class="application">Recoll</span>
          indexing to multithreading.</p>
          <p>The threads configuration is controlled by two
          configuration file parameters.</p>
          <div class="variablelist">
            <dl class="variablelist">
              <dt><span class="term"><code class=
              "varname">thrQSizes</code></span></dt>
              <dd>
                <p>This variable defines the job input queues
                configuration. There are three possible queues for
                stages 2, 3 and 4, and this parameter should give
                the queue depth for each stage (three integer
                values). If a value of -1 is used for a given
                stage, no queue is used, and the thread will go on
                performing the next stage. In practise, deep queues
                have not been shown to increase performance. A
                value of 0 for the first queue tells <span class=
                "application">Recoll</span> to perform
                autoconfiguration (no need for anything else in
                this case, thrTCounts is not used) - this is the
                default configuration.</p>
              </dd>
              <dt><span class="term"><code class=
              "varname">thrTCounts</code></span></dt>
              <dd>
                <p>This defines the number of threads used for each
                stage. If a value of -1 is used for one of the
                queue depths, the corresponding thread count is
                ignored. It makes no sense to use a value other
                than 1 for the last stage because updating the
                <span class="application">Xapian</span> index is
                necessarily single-threaded (and protected by a
                mutex).</p>
              </dd>
            </dl>
          </div>
          <div class="note" style=
          "margin-left: 0.5in; margin-right: 0.5in;">
            <h3 class="title">Note</h3>
            <p>If the first value in <code class=
            "varname">thrQSizes</code> is 0, <code class=
            "varname">thrTCounts</code> is ignored.</p>
          </div>
          <p>The following example would use three queues (of depth
          2), and 4 threads for converting source documents, 2 for
          processing their text, and one to update the index. This
          was tested to be the best configuration on the test
          system (quadri-processor with multiple disks).</p>
          <pre class="programlisting">
          thrQSizes = 2 2 2
          thrTCounts =  4 2 1
        </pre>
          <p>The following example would use a single queue, and
          the complete processing for each document would be
          performed by a single thread (several documents will
          still be processed in parallel in most cases). The
          threads will use mutual exclusion when entering the index
          update stage. In practise the performance would be close
          to the precedent case in general, but worse in certain
          cases (e.g. a Zip archive would be performed purely
          sequentially), so the previous approach is preferred.
          YMMV... The 2 last values for thrTCounts are ignored.</p>
          <pre class="programlisting">
          thrQSizes = 2 -1 -1
          thrTCounts =  6 1 1
        </pre>
          <p>The following example would disable multithreading.
          Indexing will be performed by a single thread.</p>
          <pre class="programlisting">
          thrQSizes = -1 -1 -1
        </pre>
        </div>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name="RCL.INDEXING.CONFIG.GUI"
                id="RCL.INDEXING.CONFIG.GUI"></a>2.3.4.&nbsp;The
                index configuration GUI</h3>
              </div>
            </div>
          </div>
          <p>Most parameters for a given index configuration can be
          set from a <span class=
          "command"><strong>recoll</strong></span> GUI running on
          this configuration (either as default, or by setting
          <code class="envar">RECOLL_CONFDIR</code> or the
          <code class="option">-c</code> option.)</p>
          <p>The interface is started from the <span class=
          "guimenu">Preferences</span> → <span class=
          "guimenuitem">Index Configuration</span> menu entry. It
          is divided in four tabs, <span class="guilabel">Global
          parameters</span>, <span class="guilabel">Local
          parameters</span>, <span class="guilabel">Web
          history</span> (which is explained in the next section)
          and <span class="guilabel">Search parameters</span>.</p>
          <p>The <span class="guilabel">Global parameters</span>
          tab allows setting global variables, like the lists of
          top directories, skipped paths, or stemming
          languages.</p>
          <p>The <span class="guilabel">Local parameters</span> tab
          allows setting variables that can be redefined for
          subdirectories. This second tab has an initially empty
          list of customisation directories, to which you can add.
          The variables are then set for the currently selected
          directory (or at the top level if the empty line is
          selected).</p>
          <p>The <span class="guilabel">Search parameters</span>
          section defines parameters which are used at query time,
          but are global to an index and affect all search tools,
          not only the GUI.</p>
          <p>The meaning for most entries in the interface is
          self-evident and documented by a <code class=
          "literal">ToolTip</code> popup on the text label. For
          more detail, you will need to refer to the <a class=
          "link" href="#RCL.INSTALL.CONFIG" title=
          "6.4.&nbsp;Configuration overview">configuration
          section</a> of this guide.</p>
          <p>The configuration tool normally respects the comments
          and most of the formatting inside the configuration file,
          so that it is quite possible to use it on hand-edited
          files, which you might nevertheless want to backup
          first...</p>
        </div>
      </div>
      <div class="sect1">
        <div class="titlepage">
          <div>
            <div>
              <h2 class="title" style="clear: both"><a name=
              "RCL.INDEXING.WEBQUEUE" id=
              "RCL.INDEXING.WEBQUEUE"></a>2.4.&nbsp;Indexing the
              WEB pages which you wisit.</h2>
            </div>
          </div>
        </div>
        <p>With the help of a <span class=
        "application">Firefox</span> extension, <span class=
        "application">Recoll</span> can index the Internet pages
        that you visit. The extension has a long history: it was
        initially designed for the <span class=
        "application">Beagle</span> indexer, then adapted to
        <span class="application">Recoll</span> and the
        <span class="application">Firefox</span> <span class=
        "application">XUL</span> API. A new version of the addon
        has been written to work with the <span class=
        "application">WebExtensions</span> API, which is the only
        one supported after <span class=
        "application">Firefox</span> version 57.</p>
        <p>The extension works by copying visited WEB pages to an
        indexing queue directory, which <span class=
        "application">Recoll</span> then processes, indexing the
        data, storing it into a local cache, then removing the file
        from the queue.</p>
        <p>Because the WebExtensions API introduces more
        constraints to what extensions can do, the new version
        works with one more step: the files are first created in
        the browser default downloads location (typically
        <code class="filename">$HOME/Downloads</code> ), then moved
        by a script in the old queue location. The script is
        automatically executed by the <span class=
        "application">Recoll</span> indexer versions 1.23.5 and
        newer. It could conceivably be executed independantly to
        make the new browser extension compatible with an older
        <span class="application">Recoll</span> version (the script
        is named <span class=
        "command"><strong>recoll-we-move-files.py</strong></span>).</p>
        <div class="note" style=
        "margin-left: 0.5in; margin-right: 0.5in;">
          <h3 class="title">Note</h3>
          <p>For the WebExtensions-based version to work, it is
          necessary to set the <code class=
          "literal">webdownloadsdir</code> value in the
          configuration if it was changed from the default
          <code class="filename">$HOME/Downloads</code> in the
          browser preferences.</p>
        </div>
        <p>The visited WEB pages indexing feature can be enabled on
        the <span class="application">Recoll</span> side from the
        GUI <span class="guilabel">Index configuration</span>
        panel, or by editing the configuration file (set
        <code class="varname">processwebqueue</code> to 1).</p>
        <p>A current pointer to the extension can be found, along
        with up-to-date instructions, on the <a class="ulink" href=
        "https://www.lesbonscomptes.com/recoll/faqsandhowtos/IndexWebHistory"
        target="_top">Recoll wiki</a>.</p>
        <p>A copy of the indexed WEB pages is retained by Recoll in
        a local cache (from which previews can be fetched). The
        cache size can be adjusted from the <span class=
        "guilabel">Index configuration</span> / <span class=
        "guilabel">Web history</span> panel. Once the maximum size
        is reached, old pages are purged - both from the cache and
        the index - to make room for new ones, so you need to
        explicitly archive in some other place the pages that you
        want to keep indefinitely.</p>
      </div>
      <div class="sect1">
        <div class="titlepage">
          <div>
            <div>
              <h2 class="title" style="clear: both"><a name=
              "RCL.INDEXING.EXTATTR" id=
              "RCL.INDEXING.EXTATTR"></a>2.5.&nbsp;Extended
              attributes data</h2>
            </div>
          </div>
        </div>
        <p>User extended attributes are named pieces of information
        that most modern file systems can attach to any file.</p>
        <p><span class="application">Recoll</span> versions 1.19
        and later process extended attributes as document fields by
        default. For older versions, this has to be activated at
        build time.</p>
        <p>A <a class="ulink" href=
        "http://www.freedesktop.org/wiki/CommonExtendedAttributes"
        target="_top">freedesktop standard</a> defines a few
        special attributes, which are handled as such by
        <span class="application">Recoll</span>:</p>
        <div class="variablelist">
          <dl class="variablelist">
            <dt><span class="term">mime_type</span></dt>
            <dd>
              <p>If set, this overrides any other determination of
              the file MIME type.</p>
            </dd>
            <dt><span class="term">charset</span></dt>
            <dd>
              <p>If set, this defines the file character set
              (mostly useful for plain text files).</p>
            </dd>
          </dl>
        </div>
        <p>By default, other attributes are handled as <span class=
        "application">Recoll</span> fields. On Linux, the
        <code class="literal">user</code> prefix is removed from
        the name. This can be configured more precisely inside the
        <a class="link" href="#RCL.INSTALL.CONFIG.FIELDS" title=
        "6.4.3.&nbsp;The fields file"><code class=
        "filename">fields</code> configuration file</a>.</p>
      </div>
      <div class="sect1">
        <div class="titlepage">
          <div>
            <div>
              <h2 class="title" style="clear: both"><a name=
              "RCL.INDEXING.EXTTAGS" id=
              "RCL.INDEXING.EXTTAGS"></a>2.6.&nbsp;Importing
              external tags</h2>
            </div>
          </div>
        </div>
        <p>During indexing, it is possible to import metadata for
        each file by executing commands. For example, this could
        extract user tag data for the file and store it in a field
        for indexing.</p>
        <p>See the <a class="link" href=
        "#RCL.INSTALL.CONFIG.RECOLLCONF.METADATACMDS">section about
        the <code class="literal">metadatacmds</code> field</a> in
        the main configuration chapter for a description of the
        configuration syntax.</p>
        <p>As an example, if you would want <span class=
        "application">Recoll</span> to use tags managed by
        <span class="application">tmsu</span>, you would add the
        following to the configuration file:</p>
        <pre class="programlisting">[/some/area/of/the/fs]
      metadatacmds = ; tags = tmsu tags %f
      </pre>
        <div class="note" style=
        "margin-left: 0.5in; margin-right: 0.5in;">
          <h3 class="title">Note</h3>
          <p>Depending on the <span class="application">tmsu</span>
          version, you may need/want to add options like
          <code class="literal">--database=/some/db</code>.</p>
        </div>
        <p>You may want to restrict this processing to a subset of
        the directory tree, because it may slow down indexing a bit
        (<code class="literal">[some/area/of/the/fs]</code>).</p>
        <p>Note the initial semi-colon after the equal sign.</p>
        <p>In the example above, the output of <span class=
        "command"><strong>tmsu</strong></span> is used to set a
        field named <code class="literal">tags</code>. The field
        name is arbitrary and could be <code class=
        "literal">tmsu</code> or <code class=
        "literal">myfield</code> just the same, but <code class=
        "literal">tags</code> is an alias for the standard
        <span class="application">Recoll</span> <code class=
        "literal">keywords</code> field, and the <span class=
        "command"><strong>tmsu</strong></span> output will just
        augment its contents. This will avoid the need to extend
        the <a class="link" href="#RCL.PROGRAM.FIELDS" title=
        "5.2.&nbsp;Field data processing">field
        configuration</a>.</p>
        <p>Once re-indexing is performed (you'll need to force the
        file reindexing, <span class="application">Recoll</span>
        will not detect the need by itself), you will be able to
        search from the query language, through any of its aliases:
        <code class="literal">tags:some/alternate/values</code> or
        <code class="literal">tags:all,these,values</code> (the
        compact field search syntax is supported for recoll 1.20
        and later. For older versions, you would need to repeat the
        <code class="literal">tags:</code> specifier for each term,
        e.g. <code class="literal">tags:some OR
        tags:alternate</code>).</p>
        <p>You should be aware that tags changes will not be
        detected by the indexer if the file itself did not change.
        One possible workaround would be to update the file
        <code class="literal">ctime</code> when you modify the
        tags, which would be consistent with how extended
        attributes function. A pair of <span class=
        "command"><strong>chmod</strong></span> commands could
        accomplish this, or a <code class="literal">touch -a</code>
        . Alternatively, just couple the tag update with a
        <code class="literal">recollindex -e -i
        filename.</code></p>
      </div>
      <div class="sect1">
        <div class="titlepage">
          <div>
            <div>
              <h2 class="title" style="clear: both"><a name=
              "RCL.INDEXING.PDF" id=
              "RCL.INDEXING.PDF"></a>2.7.&nbsp;The PDF input
              handler</h2>
            </div>
          </div>
        </div>
        <p>The PDF format is very important for scientific and
        technical documentation, and document archival. It has
        extensive facilities for storing metadata along with the
        document, and these facilities are actually used in the
        real world.</p>
        <p>In consequence, the <code class=
        "filename">rclpdf.py</code> PDF input handler has more
        complex capabilities than most others, and it is also more
        configurable. Specifically, <code class=
        "filename">rclpdf.py</code> can automatically use
        <span class="application">tesseract</span> to perform OCR
        if the document text is empty, it can be configured to
        extract specific metadata tags from an XMP packet, and to
        extract PDF attachments.</p>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name="RCL.INDEXING.PDF.OCR"
                id="RCL.INDEXING.PDF.OCR"></a>2.7.1.&nbsp;OCR with
                Tesseract</h3>
              </div>
            </div>
          </div>
          <p>If both <span class="application">tesseract</span> and
          <span class="command"><strong>pdftoppm</strong></span>
          (generally from the <span class=
          "application">poppler-utils</span> package) are
          installed, the PDF handler may attempt OCR on PDF files
          with no text content. This is controlled by the <a class=
          "link" href=
          "#RCL.INSTALL.CONFIG.RECOLLCONF.PDFOCR">pdfocr</a>
          configuration variable, which is false by default because
          OCR is very slow.</p>
          <p>The choice of language is very important for
          successfull OCR. Recoll has currently no way to determine
          this from the document itself. You can set the language
          to use through the contents of a <code class=
          "filename">.ocrpdflang</code> text file in the same
          directory as the PDF document, or through the
          <code class="envar">RECOLL_TESSERACT_LANG</code>
          environment variable, or through the contents of an
          <code class="filename">ocrpdf</code> text file inside the
          configuration directory. If none of the above are used,
          <span class="application">Recoll</span> will try to guess
          the language from the NLS environment.</p>
        </div>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name="RCL.INDEXING.PDF.XMP"
                id="RCL.INDEXING.PDF.XMP"></a>2.7.2.&nbsp;XMP
                fields extraction</h3>
              </div>
            </div>
          </div>
          <p>The <code class="filename">rclpdf.py</code> script in
          <span class="application">Recoll</span> version 1.23.2
          and later can extract XMP metadata fields by executing
          the <span class="command"><strong>pdfinfo</strong></span>
          command (usually found with <span class=
          "application">poppler-utils</span>). This is controlled
          by the <a class="link" href=
          "#RCL.INSTALL.CONFIG.RECOLLCONF.PDFEXTRAMETA">pdfextrameta</a>
          configuration variable, which specifies which tags to
          extract and, possibly, how to rename them.</p>
          <p>The <a class="link" href=
          "#RCL.INSTALL.CONFIG.RECOLLCONF.PDFEXTRAMETAFIX">pdfextrametafix</a>
          variable can be used to designate a file with Python code
          to edit the metadata fields (available for <span class=
          "application">Recoll</span> 1.23.3 and later. 1.23.2 has
          equivalent code inside the handler script). Example:</p>
          <pre class="programlisting">import sys
        import re

        class MetaFixer(object):
        def __init__(self):
        pass

        def metafix(self, nm, txt):
        if nm == 'bibtex:pages':
        txt = re.sub(r'--', '-', txt)
        elif nm == 'someothername':
        # do something else
        pass
        elif nm == 'stillanother':
        # etc.
        pass
        
        return txt
        def wrapup(self, metaheaders):
        pass
        </pre>
          <p>If the 'metafix()' method is defined, it is called for
          each metadata field. A new MetaFixer object is created
          for each PDF document (so the object can keep state for,
          for example, eliminating duplicate values). If the
          'wrapup()' method is defined, it is called at the end of
          XMP fields processing with the whole metadata as
          parameter, as an array of '(nm, val)' pairs, allowing an
          alternate approach for editing or adding/deleting
          fields.</p>
        </div>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name="RCL.INDEXING.PDF.ATTACH"
                id="RCL.INDEXING.PDF.ATTACH"></a>2.7.3.&nbsp;PDF
                attachment indexing</h3>
              </div>
            </div>
          </div>
          <p>If <span class="application">pdftk</span> is
          installed, and if the the <a class="link" href=
          "#RCL.INSTALL.CONFIG.RECOLLCONF.PDFATTACH">pdfattach</a>
          configuration variable is set, the PDF input handler will
          try to extract PDF attachements for indexing as
          sub-documents of the PDF file. This is disabled by
          default, because it slows down PDF indexing a bit even if
          not one attachment is ever found (PDF attachments are
          uncommon in my experience).</p>
        </div>
      </div>
      <div class="sect1">
        <div class="titlepage">
          <div>
            <div>
              <h2 class="title" style="clear: both"><a name=
              "RCL.INDEXING.PERIODIC" id=
              "RCL.INDEXING.PERIODIC"></a>2.8.&nbsp;Periodic
              indexing</h2>
            </div>
          </div>
        </div>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name=
                "RCL.INDEXING.PERIODIC.EXEC" id=
                "RCL.INDEXING.PERIODIC.EXEC"></a>2.8.1.&nbsp;Running
                indexing</h3>
              </div>
            </div>
          </div>
          <p>Indexing is always performed by the <span class=
          "command"><strong>recollindex</strong></span> program,
          which can be started either from the command line or from
          the <span class="guimenu">File</span> menu in the
          <span class="command"><strong>recoll</strong></span> GUI
          program. When started from the GUI, the indexing will run
          on the same configuration <span class=
          "command"><strong>recoll</strong></span> was started on.
          When started from the command line, <span class=
          "command"><strong>recollindex</strong></span> will use
          the <code class="envar">RECOLL_CONFDIR</code> variable or
          accept a <code class="option">-c</code> <em class=
          "replaceable"><code>confdir</code></em> option to specify
          a non-default configuration directory.</p>
          <p>If the <span class=
          "command"><strong>recoll</strong></span> program finds no
          index when it starts, it will automatically start
          indexing (except if canceled).</p>
          <p>The <span class=
          "command"><strong>recollindex</strong></span> indexing
          process can be interrupted by sending an interrupt
          (<span class="keysym">Ctrl-C</span>, SIGINT) or terminate
          (SIGTERM) signal. Some time may elapse before the process
          exits, because it needs to properly flush and close the
          index. This can also be done from the <span class=
          "command"><strong>recoll</strong></span> GUI <span class=
          "guimenu">File</span> → <span class="guimenuitem">Stop
          Indexing</span> menu entry.</p>
          <p>After such an interruption, the index will be somewhat
          inconsistent because some operations which are normally
          performed at the end of the indexing pass will have been
          skipped (for example, the stemming and spelling databases
          will be inexistant or out of date). You just need to
          restart indexing at a later time to restore consistency.
          The indexing will restart at the interruption point (the
          full file tree will be traversed, but files that were
          indexed up to the interruption and for which the index is
          still up to date will not need to be reindexed).</p>
          <p><span class=
          "command"><strong>recollindex</strong></span> has a
          number of other options which are described in its man
          page. Only a few will be described here.</p>
          <p>Option <code class="option">-z</code> will reset the
          index when starting. This is almost the same as
          destroying the index files (the nuance is that the
          <span class="application">Xapian</span> format version
          will not be changed).</p>
          <p>Option <code class="option">-Z</code> will force the
          update of all documents without resetting the index
          first. This will not have the "clean start" aspect of
          <code class="option">-z</code>, but the advantage is that
          the index will remain available for querying while it is
          rebuilt, which can be a significant advantage if it is
          very big (some installations need days for a full index
          rebuild).</p>
          <p>Option <code class="option">-k</code> will force
          retrying files which previously failed to be indexed, for
          example because of a missing helper program.</p>
          <p>Of special interest also, maybe, are the <code class=
          "option">-i</code> and <code class="option">-f</code>
          options. <code class="option">-i</code> allows indexing
          an explicit list of files (given as command line
          parameters or read on <code class=
          "literal">stdin</code>). <code class="option">-f</code>
          tells <span class=
          "command"><strong>recollindex</strong></span> to ignore
          file selection parameters from the configuration.
          Together, these options allow building a custom file
          selection process for some area of the file system, by
          adding the top directory to the <code class=
          "varname">skippedPaths</code> list and using an
          appropriate file selection method to build the file list
          to be fed to <span class=
          "command"><strong>recollindex</strong></span>
          <code class="option">-if</code>. Trivial example:</p>
          <pre class="programlisting">
          find . -name indexable.txt -print | recollindex -if
        </pre>
          <p><span class=
          "command"><strong>recollindex</strong></span>
          <code class="option">-i</code> will not descend into
          subdirectories specified as parameters, but just add them
          as index entries. It is up to the external file selection
          method to build the complete file list.</p>
        </div>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name=
                "RCL.INDEXING.PERIODIC.AUTOMAT" id=
                "RCL.INDEXING.PERIODIC.AUTOMAT"></a>2.8.2.&nbsp;Using
                <span class="command"><strong>cron</strong></span>
                to automate indexing</h3>
              </div>
            </div>
          </div>
          <p>The most common way to set up indexing is to have a
          cron task execute it every night. For example the
          following <code class="filename">crontab</code> entry
          would do it every day at 3:30AM (supposing <span class=
          "command"><strong>recollindex</strong></span> is in your
          PATH):</p>
          <pre class="screen">
        30 3 * * * recollindex &gt; /some/tmp/dir/recolltrace 2&gt;&amp;1
        </pre>
          <p>Or, using <span class=
          "command"><strong>anacron</strong></span>:</p>
          <pre class="screen">
        1  15  su mylogin -c "recollindex recollindex &gt; /tmp/rcltraceme 2&gt;&amp;1"
        </pre>
          <p>As of version 1.17 the <span class=
          "application">Recoll</span> GUI has dialogs to manage
          <code class="filename">crontab</code> entries for
          <span class=
          "command"><strong>recollindex</strong></span>. You can
          reach them from the <span class=
          "guimenu">Preferences</span> → <span class=
          "guimenuitem">Indexing Schedule</span> menu. They only
          work with the good old <span class=
          "command"><strong>cron</strong></span>, and do not give
          access to all features of <span class=
          "command"><strong>cron</strong></span> scheduling.</p>
          <p>The usual command to edit your <code class=
          "filename">crontab</code> is <span class=
          "command"><strong>crontab</strong></span> <code class=
          "option">-e</code> (which will usually start the
          <span class="command"><strong>vi</strong></span> editor
          to edit the file). You may have more sophisticated tools
          available on your system.</p>
          <p>Please be aware that there may be differences between
          your usual interactive command line environment and the
          one seen by crontab commands. Especially the PATH
          variable may be of concern. Please check the crontab
          manual pages about possible issues.</p>
        </div>
      </div>
      <div class="sect1">
        <div class="titlepage">
          <div>
            <div>
              <h2 class="title" style="clear: both"><a name=
              "RCL.INDEXING.MONITOR" id=
              "RCL.INDEXING.MONITOR"></a>2.9.&nbsp;Real time
              indexing</h2>
            </div>
          </div>
        </div>
        <p>Real time monitoring/indexing is performed by starting
        the <span class=
        "command"><strong>recollindex</strong></span> <code class=
        "option">-m</code> command. With this option, <span class=
        "command"><strong>recollindex</strong></span> will detach
        from the terminal and become a daemon, permanently
        monitoring file changes and updating the index.</p>
        <p>While it is convenient that data is indexed in real
        time, repeated indexing can generate a significant load on
        the system when files such as email folders change. Also,
        monitoring large file trees by itself significantly taxes
        system resources. You probably do not want to enable it if
        your system is short on resources. Periodic indexing is
        adequate in most cases.</p>
        <p>As of <span class="application">Recoll</span> 1.24, you
        can set the <a class="link" href=
        "#RCL.INSTALL.CONFIG.RECOLLCONF.MONITORDIRS">monitordirs</a>
        configuration variable to specify that only a subset of
        your indexed files will be monitored for instant indexing.
        In this situation, an incremental pass on the full tree can
        be triggered by either restarting the indexer, or just
        running <span class=
        "command"><strong>recollindex</strong></span>, which will
        notify the running process. The <span class=
        "command"><strong>recoll</strong></span> GUI also has a
        menu entry for this.</p>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name=
                "RCL.INDEXING.MONITOR.START" id=
                "RCL.INDEXING.MONITOR.START"></a>2.9.1.&nbsp;Real
                time indexing: automatic daemon start</h3>
              </div>
            </div>
          </div>
          <p>Under <span class="application">KDE</span>,
          <span class="application">Gnome</span> and some other
          desktop environments, the daemon can automatically
          started when you log in, by creating a desktop file
          inside the <code class=
          "filename">~/.config/autostart</code> directory. This can
          be done for you by the <span class=
          "application">Recoll</span> GUI. Use the <span class=
          "guimenu">Preferences-&gt;Indexing Schedule</span>
          menu.</p>
          <p>With older <span class="application">X11</span>
          setups, starting the daemon is normally performed as part
          of the user session script.</p>
          <p>The <code class="filename">rclmon.sh</code> script can
          be used to easily start and stop the daemon. It can be
          found in the <code class="filename">examples</code>
          directory (typically <code class=
          "filename">/usr/local/[share/]recoll/examples</code>).</p>
          <p>For example, my out of fashion <span class=
          "application">xdm</span>-based session has a <code class=
          "filename">.xsession</code> script with the following
          lines at the end:</p>
          <pre class="programlisting">recollconf=$HOME/.recoll-home
        recolldata=/usr/local/share/recoll
        RECOLL_CONFDIR=$recollconf $recolldata/examples/rclmon.sh start

        fvwm 

        </pre>
          <p>The indexing daemon gets started, then the window
          manager, for which the session waits.</p>
          <p>By default the indexing daemon will monitor the state
          of the X11 session, and exit when it finishes, it is not
          necessary to kill it explicitly. (The <span class=
          "application">X11</span> server monitoring can be
          disabled with option <code class="option">-x</code> to
          <span class=
          "command"><strong>recollindex</strong></span>).</p>
          <p>If you use the daemon completely out of an
          <span class="application">X11</span> session, you need to
          add option <code class="option">-x</code> to disable
          <span class="application">X11</span> session monitoring
          (else the daemon will not start).</p>
        </div>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name=
                "RCL.INDEXING.MONITOR.DETAILS" id=
                "RCL.INDEXING.MONITOR.DETAILS"></a>2.9.2.&nbsp;Real
                time indexing: miscellaneous details</h3>
              </div>
            </div>
          </div>
          <p>By default, the messages from the indexing daemon will
          be sent to the same file as those from the interactive
          commands (<code class="literal">logfilename</code>). You
          may want to change this by setting the <code class=
          "varname">daemlogfilename</code> and <code class=
          "varname">daemloglevel</code> configuration parameters.
          Also the log file will only be truncated when the daemon
          starts. If the daemon runs permanently, the log file may
          grow quite big, depending on the log level.</p>
          <p>When building <span class="application">Recoll</span>,
          the real time indexing support can be customised during
          package <a class="link" href="#RCL.INSTALL.BUILDING"
          title="6.3.&nbsp;Building from source">configuration</a>
          with the <code class="option">--with[out]-fam</code> or
          <code class="option">--with[out]-inotify</code> options.
          The default is currently to include <span class=
          "application">inotify</span> monitoring on systems that
          support it, and, as of <span class=
          "application">Recoll</span> 1.17, <span class=
          "application">gamin</span> support on <span class=
          "application">FreeBSD</span>.</p>
          <div class="note" style=
          "margin-left: 0.5in; margin-right: 0.5in;">
            <h3 class="title">Increasing resources for inotify</h3>
            <p>On Linux systems, monitoring a big tree may need
            increasing the resources available to inotify, which
            are normally defined in <code class=
            "filename">/etc/sysctl.conf</code>.</p>
            <pre class="programlisting">
          ### inotify
          #
          # cat  /proc/sys/fs/inotify/max_queued_events   - 16384
          # cat  /proc/sys/fs/inotify/max_user_instances  - 128
          # cat  /proc/sys/fs/inotify/max_user_watches    - 16384
          #
          # -- Change to:
          #
          fs.inotify.max_queued_events=32768
          fs.inotify.max_user_instances=256
          fs.inotify.max_user_watches=32768
        </pre>
            <p>Especially, you will need to trim your tree or
            adjust the <code class=
            "literal">max_user_watches</code> value if indexing
            exits with a message about errno <code class=
            "literal">ENOSPC</code> (28) from <code class=
            "function">inotify_add_watch</code>.</p>
          </div>
          <div class="note" style=
          "margin-left: 0.5in; margin-right: 0.5in;">
            <h3 class="title">Slowing down the reindexing rate for
            fast changing files</h3>
            <p>When using the real time monitor, it may happen that
            some files need to be indexed, but change so often that
            they impose an excessive load for the system.</p>
            <p><span class="application">Recoll</span> provides a
            configuration option to specify the minimum time before
            which a file, specified by a wildcard pattern, cannot
            be reindexed. See the <code class=
            "varname">mondelaypatterns</code> parameter in the
            <a class="link" href=
            "#RCL.INSTALL.CONFIG.RECOLLCONF.MISC" title=
            "6.4.2.5.&nbsp;Miscellaneous parameters">configuration
            section</a>.</p>
          </div>
        </div>
      </div>
    </div>
    <div class="chapter">
      <div class="titlepage">
        <div>
          <div>
            <h1 class="title"><a name="RCL.SEARCH" id=
            "RCL.SEARCH"></a>Chapter&nbsp;3.&nbsp;Searching</h1>
          </div>
        </div>
      </div>
      <div class="sect1">
        <div class="titlepage">
          <div>
            <div>
              <h2 class="title" style="clear: both"><a name=
              "RCL.SEARCH.GUI" id=
              "RCL.SEARCH.GUI"></a>3.1.&nbsp;Searching with the Qt
              graphical user interface</h2>
            </div>
          </div>
        </div>
        <p>The <span class="command"><strong>recoll</strong></span>
        program provides the main user interface for searching. It
        is based on the <span class="application">Qt</span>
        library.</p>
        <p><span class="command"><strong>recoll</strong></span> has
        two search modes:</p>
        <div class="itemizedlist">
          <ul class="itemizedlist" style="list-style-type: disc;">
            <li class="listitem">
              <p>Simple search (the default, on the main screen)
              has a single entry field where you can enter multiple
              words.</p>
            </li>
            <li class="listitem">
              <p>Advanced search (a panel accessed through the
              <span class="guilabel">Tools</span> menu or the
              toolbox bar icon) has multiple entry fields, which
              you may use to build a logical condition, with
              additional filtering on file type, location in the
              file system, modification date, and size.</p>
            </li>
          </ul>
        </div>
        <p>In most cases, you can enter the terms as you think
        them, even if they contain embedded punctuation or other
        non-textual characters. For example, <span class=
        "application">Recoll</span> can handle things like email
        addresses, or arbitrary cut and paste from another text
        window, punctation and all.</p>
        <p>The main case where you should enter text differently
        from how it is printed is for east-asian languages
        (Chinese, Japanese, Korean). Words composed of single or
        multiple characters should be entered separated by white
        space in this case (they would typically be printed without
        white space).</p>
        <p>Some searches can be quite complex, and you may want to
        re-use them later, perhaps with some tweaking. <span class=
        "application">Recoll</span> versions 1.21 and later can
        save and restore searches, using XML files. See <a class=
        "link" href="#RCL.SEARCH.SAVING" title=
        "3.1.14.&nbsp;Saving and restoring queries (1.21 and later)">
        Saving and restoring queries</a>.</p>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name="RCL.SEARCH.GUI.SIMPLE"
                id="RCL.SEARCH.GUI.SIMPLE"></a>3.1.1.&nbsp;Simple
                search</h3>
              </div>
            </div>
          </div>
          <div class="procedure">
            <ol class="procedure" type="1">
              <li class="step">
                <p>Start the <span class=
                "command"><strong>recoll</strong></span>
                program.</p>
              </li>
              <li class="step">
                <p>Possibly choose a search mode: <span class=
                "guilabel">Any term</span>, <span class=
                "guilabel">All terms</span>, <span class=
                "guilabel">File name</span> or <span class=
                "guilabel">Query language</span>.</p>
              </li>
              <li class="step">
                <p>Enter search term(s) in the text field at the
                top of the window.</p>
              </li>
              <li class="step">
                <p>Click the <span class="guilabel">Search</span>
                button or hit the <span class=
                "keycap"><strong>Enter</strong></span> key to start
                the search.</p>
              </li>
            </ol>
          </div>
          <p>The initial default search mode is <span class=
          "guilabel">Query language</span>. Without special
          directives, this will look for documents containing all
          of the search terms (the ones with more terms will get
          better scores), just like the <span class="guilabel">All
          terms</span> mode. <span class="guilabel">Any term</span>
          will search for documents where at least one of the terms
          appear.</p>
          <p>The <span class="guilabel">Query Language</span>
          features are described in <a class="link" href=
          "#RCL.SEARCH.LANG" title="3.6.&nbsp;The query language">a
          separate section</a>.</p>
          <p>All search modes allow terms to be expanded with
          wildcards characters (<code class="literal">*</code>,
          <code class="literal">?</code>, <code class=
          "literal">[]</code>). See the <a class="link" href=
          "#RCL.SEARCH.WILDCARDS" title=
          "3.8.1.&nbsp;More about wildcards">section about
          wildcards</a> for more details.</p>
          <p>The <span class="guilabel">File name</span> search
          mode will specifically look for file names. The point of
          having a separate file name search is that wild card
          expansion can be performed more efficiently on a small
          subset of the index (allowing wild cards on the left of
          terms without excessive penality). Things to know:</p>
          <div class="itemizedlist">
            <ul class="itemizedlist" style=
            "list-style-type: disc;">
              <li class="listitem">
                <p>White space in the entry should match white
                space in the file name, and is not treated
                specially.</p>
              </li>
              <li class="listitem">
                <p>The search is insensitive to character case and
                accents, independantly of the type of index.</p>
              </li>
              <li class="listitem">
                <p>An entry without any wild card character and not
                capitalized will be prepended and appended with '*'
                (ie: <em class="replaceable"><code>etc</code></em>
                -&gt; <em class=
                "replaceable"><code>*etc*</code></em>, but
                <em class="replaceable"><code>Etc</code></em> -&gt;
                <em class="replaceable"><code>etc</code></em>).</p>
              </li>
              <li class="listitem">
                <p>If you have a big index (many files),
                excessively generic fragments may result in
                inefficient searches.</p>
              </li>
            </ul>
          </div>
          <p>In all modes except <span class="guilabel">File
          name</span>, you can search for exact phrases (adjacent
          words in a given order) by enclosing the input inside
          double quotes. Ex: <code class="literal">"virtual
          reality"</code>.</p>
          <p>When using a stripped index (the default), character
          case has no influence on search, except that you can
          disable stem expansion for any term by capitalizing it.
          Ie: a search for <code class="literal">floor</code> will
          also normally look for <code class=
          "literal">flooring</code>, <code class=
          "literal">floored</code>, etc., but a search for
          <code class="literal">Floor</code> will only look for
          <code class="literal">floor</code>, in any character
          case. Stemming can also be disabled globally in the
          preferences. When using a raw index, <a class="link"
          href="#RCL.SEARCH.CASEDIAC" title=
          "3.7.&nbsp;Search case and diacritics sensitivity">the
          rules are a bit more complicated</a>.</p>
          <p><span class="application">Recoll</span> remembers the
          last few searches that you performed. You can directly
          access the search history by clicking the clock button on
          the right of the search entry, while the latter is empty.
          Otherwise, the history is used for entry completion (see
          next). Only the search texts are remembered, not the mode
          (all/any/file name).</p>
          <p>While text is entered in the search area, <span class=
          "command"><strong>recoll</strong></span> will display
          possible completions, filtered from the history and the
          index search terms. This can be disabled with a GUI
          Preferences option.</p>
          <p>Double-clicking on a word in the result list or a
          preview window will insert it into the simple search
          entry field.</p>
          <p>You can cut and paste any text into an <span class=
          "guilabel">All terms</span> or <span class="guilabel">Any
          term</span> search field, punctuation, newlines and all -
          except for wildcard characters (single <code class=
          "literal">?</code> characters are ok). <span class=
          "application">Recoll</span> will process it and produce a
          meaningful search. This is what most differentiates this
          mode from the <span class="guilabel">Query
          Language</span> mode, where you have to care about the
          syntax.</p>
          <p>You can use the <a class="link" href=
          "#RCL.SEARCH.GUI.COMPLEX" title=
          "3.1.8.&nbsp;Complex/advanced search"><span class=
          "guimenu">Tools</span> → <span class=
          "guimenuitem">Advanced search</span></a> dialog for more
          complex searches.</p>
        </div>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name="RCL.SEARCH.GUI.RESLIST"
                id="RCL.SEARCH.GUI.RESLIST"></a>3.1.2.&nbsp;The
                default result list</h3>
              </div>
            </div>
          </div>
          <p>After starting a search, a list of results will
          instantly be displayed in the main list window.</p>
          <p>By default, the document list is presented in order of
          relevance (how well the system estimates that the
          document matches the query). You can sort the result by
          ascending or descending date by using the vertical arrows
          in the toolbar.</p>
          <p>Clicking on the <code class="literal">Preview</code>
          link for an entry will open an internal preview window
          for the document. Further <code class=
          "literal">Preview</code> clicks for the same search will
          open tabs in the existing preview window. You can use
          <span class="keycap"><strong>Shift</strong></span>+Click
          to force the creation of another preview window, which
          may be useful to view the documents side by side. (You
          can also browse successive results in a single preview
          window by typing <span class=
          "keycap"><strong>Shift</strong></span>+<span class=
          "keycap"><strong>ArrowUp/Down</strong></span> in the
          window).</p>
          <p>Clicking the <code class="literal">Open</code> link
          will start an external viewer for the document. By
          default, <span class="application">Recoll</span> lets the
          desktop choose the appropriate application for most
          document types (there is a short list of exceptions, see
          further). If you prefer to completely customize the
          choice of applications, you can uncheck the <span class=
          "guilabel">Use desktop preferences</span> option in the
          GUI preferences dialog, and click the <span class=
          "guilabel">Choose editor applications</span> button to
          adjust the predefined <span class=
          "application">Recoll</span> choices. The tool accepts
          multiple selections of MIME types (e.g. to set up the
          editor for the dozens of office file types).</p>
          <p>Even when <span class="guilabel">Use desktop
          preferences</span> is checked, there is a small list of
          exceptions, for MIME types where the <span class=
          "application">Recoll</span> choice should override the
          desktop one. These are applications which are well
          integrated with <span class="application">Recoll</span>,
          especially <span class="application">evince</span> for
          viewing PDF and Postscript files because of its support
          for opening the document at a specific page and passing a
          search string as an argument. Of course, you can edit the
          list (in the GUI preferences) if you would prefer to lose
          the functionality and use the standard desktop tool.</p>
          <p>You may also change the choice of applications by
          editing the <a class="link" href=
          "#RCL.INSTALL.CONFIG.MIMEVIEW" title=
          "6.4.6.&nbsp;The mimeview file"><code class=
          "filename">mimeview</code></a> configuration file if you
          find this more convenient.</p>
          <p>Each result entry also has a right-click menu with an
          <span class="guilabel">Open With</span> entry. This lets
          you choose an application from the list of those which
          registered with the desktop for the document MIME
          type.</p>
          <p>The <code class="literal">Preview</code> and
          <code class="literal">Open</code> edit links may not be
          present for all entries, meaning that <span class=
          "application">Recoll</span> has no configured way to
          preview a given file type (which was indexed by name
          only), or no configured external editor for the file
          type. This can sometimes be adjusted simply by tweaking
          the <a class="link" href="#RCL.INSTALL.CONFIG.MIMEMAP"
          title="6.4.4.&nbsp;The mimemap file"><code class=
          "filename">mimemap</code></a> and <a class="link" href=
          "#RCL.INSTALL.CONFIG.MIMEVIEW" title=
          "6.4.6.&nbsp;The mimeview file"><code class=
          "filename">mimeview</code></a> configuration files (the
          latter can be modified with the user preferences
          dialog).</p>
          <p>The format of the result list entries is entirely
          configurable by using the preference dialog to <a class=
          "link" href="#RCL.SEARCH.GUI.CUSTOM.RESLIST" title=
          "3.1.15.1.&nbsp;The result list format">edit an HTML
          fragment</a>.</p>
          <p>You can click on the <code class="literal">Query
          details</code> link at the top of the results page to see
          the query actually performed, after stem expansion and
          other processing.</p>
          <p>Double-clicking on any word inside the result list or
          a preview window will insert it into the simple search
          text.</p>
          <p>The result list is divided into pages (the size of
          which you can change in the preferences). Use the arrow
          buttons in the toolbar or the links at the bottom of the
          page to browse the results.</p>
          <div class="sect3">
            <div class="titlepage">
              <div>
                <div>
                  <h4 class="title"><a name=
                  "RCL.SEARCH.GUI.RESLIST.SUGGS" id=
                  "RCL.SEARCH.GUI.RESLIST.SUGGS"></a>3.1.2.1.&nbsp;No
                  results: the spelling suggestions</h4>
                </div>
              </div>
            </div>
            <p>When a search yields no result, and if the
            <span class="application">aspell</span> dictionary is
            configured, <span class="application">Recoll</span>
            will try to check for misspellings among the query
            terms, and will propose lists of replacements. Clicking
            on one of the suggestions will replace the word and
            restart the search. You can hold any of the modifier
            keys (Ctrl, Shift, etc.) while clicking if you would
            rather stay on the suggestion screen because several
            terms need replacement.</p>
          </div>
          <div class="sect3">
            <div class="titlepage">
              <div>
                <div>
                  <h4 class="title"><a name=
                  "RCL.SEARCH.GUI.RESULTLIST.MENU" id=
                  "RCL.SEARCH.GUI.RESULTLIST.MENU"></a>3.1.2.2.&nbsp;The
                  result list right-click menu</h4>
                </div>
              </div>
            </div>
            <p>Apart from the preview and edit links, you can
            display a pop-up menu by right-clicking over a
            paragraph in the result list. This menu has the
            following entries:</p>
            <div class="itemizedlist">
              <ul class="itemizedlist" style=
              "list-style-type: disc;">
                <li class="listitem">
                  <p><span class="guilabel">Preview</span></p>
                </li>
                <li class="listitem">
                  <p><span class="guilabel">Open</span></p>
                </li>
                <li class="listitem">
                  <p><span class="guilabel">Open With</span></p>
                </li>
                <li class="listitem">
                  <p><span class="guilabel">Run Script</span></p>
                </li>
                <li class="listitem">
                  <p><span class="guilabel">Copy File
                  Name</span></p>
                </li>
                <li class="listitem">
                  <p><span class="guilabel">Copy Url</span></p>
                </li>
                <li class="listitem">
                  <p><span class="guilabel">Save to File</span></p>
                </li>
                <li class="listitem">
                  <p><span class="guilabel">Find similar</span></p>
                </li>
                <li class="listitem">
                  <p><span class="guilabel">Preview Parent
                  document</span></p>
                </li>
                <li class="listitem">
                  <p><span class="guilabel">Open Parent
                  document</span></p>
                </li>
                <li class="listitem">
                  <p><span class="guilabel">Open Snippets
                  Window</span></p>
                </li>
              </ul>
            </div>
            <p>The <span class="guilabel">Preview</span> and
            <span class="guilabel">Open</span> entries do the same
            thing as the corresponding links.</p>
            <p><span class="guilabel">Open With</span> lets you
            open the document with one of the applications claiming
            to be able to handle its MIME type (the information
            comes from the <code class="literal">.desktop</code>
            files in <code class=
            "filename">/usr/share/applications</code>).</p>
            <p><span class="guilabel">Run Script</span> allows
            starting an arbitrary command on the result file. It
            will only appear for results which are top-level files.
            See <a class="link" href="#RCL.SEARCH.GUI.RUNSCRIPT"
            title=
            "3.1.4.&nbsp;Running arbitrary commands on result files (1.20 and later)">
            further</a> for a more detailed description.</p>
            <p>The <span class="guilabel">Copy File Name</span> and
            <span class="guilabel">Copy Url</span> copy the
            relevant data to the clipboard, for later pasting.</p>
            <p><span class="guilabel">Save to File</span> allows
            saving the contents of a result document to a chosen
            file. This entry will only appear if the document does
            not correspond to an existing file, but is a
            subdocument inside such a file (ie: an email
            attachment). It is especially useful to extract
            attachments with no associated editor.</p>
            <p>The <span class="guilabel">Open/Preview Parent
            document</span> entries allow working with the higher
            level document (e.g. the email message an attachment
            comes from). <span class="application">Recoll</span> is
            sometimes not totally accurate as to what it can or
            can't do in this area. For example the <span class=
            "guilabel">Parent</span> entry will also appear for an
            email which is part of an mbox folder file, but you
            can't actually visualize the mbox (there will be an
            error dialog if you try).</p>
            <p>If the document is a top-level file, <span class=
            "guilabel">Open Parent</span> will start the default
            file manager on the enclosing filesystem directory.</p>
            <p>The <span class="guilabel">Find similar</span> entry
            will select a number of relevant term from the current
            document and enter them into the simple search field.
            You can then start a simple search, with a good chance
            of finding documents related to the current result. I
            can't remember a single instance where this function
            was actually useful to me...</p>
            <p><a name="RCL.SEARCH.GUI.RESULTLIST.MENU.SNIPPETS"
            id="RCL.SEARCH.GUI.RESULTLIST.MENU.SNIPPETS"></a>The
            <span class="guilabel">Open Snippets Window</span>
            entry will only appear for documents which support page
            breaks (typically PDF, Postscript, DVI). The snippets
            window lists extracts from the document, taken around
            search terms occurrences, along with the corresponding
            page number, as links which can be used to start the
            native viewer on the appropriate page. If the viewer
            supports it, its search function will also be primed
            with one of the search terms.</p>
          </div>
        </div>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name="RCL.SEARCH.GUI.RESTABLE"
                id="RCL.SEARCH.GUI.RESTABLE"></a>3.1.3.&nbsp;The
                result table</h3>
              </div>
            </div>
          </div>
          <p>In <span class="application">Recoll</span> 1.15 and
          newer, the results can be displayed in spreadsheet-like
          fashion. You can switch to this presentation by clicking
          the table-like icon in the toolbar (this is a toggle,
          click again to restore the list).</p>
          <p>Clicking on the column headers will allow sorting by
          the values in the column. You can click again to invert
          the order, and use the header right-click menu to reset
          sorting to the default relevance order (you can also use
          the sort-by-date arrows to do this).</p>
          <p>Both the list and the table display the same
          underlying results. The sort order set from the table is
          still active if you switch back to the list mode. You can
          click twice on a date sort arrow to reset it from
          there.</p>
          <p>The header right-click menu allows adding or deleting
          columns. The columns can be resized, and their order can
          be changed (by dragging). All the changes are recorded
          when you quit <span class=
          "command"><strong>recoll</strong></span></p>
          <p>Hovering over a table row will update the detail area
          at the bottom of the window with the corresponding
          values. You can click the row to freeze the display. The
          bottom area is equivalent to a result list paragraph,
          with links for starting a preview or a native
          application, and an equivalent right-click menu. Typing
          <span class="keycap"><strong>Esc</strong></span> (the
          Escape key) will unfreeze the display.</p>
        </div>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name=
                "RCL.SEARCH.GUI.RUNSCRIPT" id=
                "RCL.SEARCH.GUI.RUNSCRIPT"></a>3.1.4.&nbsp;Running
                arbitrary commands on result files (1.20 and
                later)</h3>
              </div>
            </div>
          </div>
          <p>Apart from the <span class="guilabel">Open</span> and
          <span class="guilabel">Open With</span> operations, which
          allow starting an application on a result document (or a
          temporary copy), based on its MIME type, it is also
          possible to run arbitrary commands on results which are
          top-level files, using the <span class="guilabel">Run
          Script</span> entry in the results pop-up menu.</p>
          <p>The commands which will appear in the <span class=
          "guilabel">Run Script</span> submenu must be defined by
          <code class="literal">.desktop</code> files inside the
          <code class="filename">scripts</code> subdirectory of the
          current configuration directory.</p>
          <p>Here follows an example of a <code class=
          "literal">.desktop</code> file, which could be named for
          example, <code class=
          "filename">~/.recoll/scripts/myscript.desktop</code> (the
          exact file name inside the directory is irrelevant):</p>
          <pre class="programlisting">
          [Desktop Entry]
          Type=Application
          Name=MyFirstScript
          Exec=/home/me/bin/tryscript %F
          MimeType=*/*
        </pre>
          <p>The <code class="literal">Name</code> attribute
          defines the label which will appear inside the
          <span class="guilabel">Run Script</span> menu. The
          <code class="literal">Exec</code> attribute defines the
          program to be run, which does not need to actually be a
          script, of course. The <code class=
          "literal">MimeType</code> attribute is not used, but
          needs to exist.</p>
          <p>The commands defined this way can also be used from
          links inside the <a class="link" href=
          "#RCL.SEARCH.GUI.CUSTOM.RESLIST.PARA" title=
          "The paragraph format">result paragraph</a>.</p>
          <p>As an example, it might make sense to write a script
          which would move the document to the trash and purge it
          from the <span class="application">Recoll</span>
          index.</p>
        </div>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name=
                "RCL.SEARCH.GUI.THUMBNAILS" id=
                "RCL.SEARCH.GUI.THUMBNAILS"></a>3.1.5.&nbsp;Displaying
                thumbnails</h3>
              </div>
            </div>
          </div>
          <p>The default format for the result list entries and the
          detail area of the result table display an icon for each
          result document. The icon is either a generic one
          determined from the MIME type, or a thumbnail of the
          document appearance. Thumbnails are only displayed if
          found in the standard <span class=
          "application">freedesktop</span> location, where they
          would typically have been created by a file manager.</p>
          <p>Recoll has no capability to create thumbnails. A
          relatively simple trick is to use the <span class=
          "guilabel">Open parent document/folder</span> entry in
          the result list popup menu. This should open a file
          manager window on the containing directory, which should
          in turn create the thumbnails (depending on your
          settings). Restarting the search should then display the
          thumbnails.</p>
          <p>There are also <a class="ulink" href=
          "https://www.lesbonscomptes.com/recoll/faqsandhowtos/ResultsThumbnails.wiki"
          target="_top">some pointers about thumbnail
          generation</a> on the <span class=
          "application">Recoll</span> wiki.</p>
        </div>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name="RCL.SEARCH.GUI.PREVIEW"
                id="RCL.SEARCH.GUI.PREVIEW"></a>3.1.6.&nbsp;The
                preview window</h3>
              </div>
            </div>
          </div>
          <p>The preview window opens when you first click a
          <code class="literal">Preview</code> link inside the
          result list.</p>
          <p>Subsequent preview requests for a given search open
          new tabs in the existing window (except if you hold the
          <span class="keycap"><strong>Shift</strong></span> key
          while clicking which will open a new window for side by
          side viewing).</p>
          <p>Starting another search and requesting a preview will
          create a new preview window. The old one stays open until
          you close it.</p>
          <p>You can close a preview tab by typing <span class=
          "keycap"><strong>Ctrl-W</strong></span> (<span class=
          "keycap"><strong>Ctrl</strong></span> + <span class=
          "keycap"><strong>W</strong></span>) in the window.
          Closing the last tab for a window will also close the
          window.</p>
          <p>Of course you can also close a preview window by using
          the window manager button in the top of the frame.</p>
          <p>You can display successive or previous documents from
          the result list inside a preview tab by typing
          <span class=
          "keycap"><strong>Shift</strong></span>+<span class=
          "keycap"><strong>Down</strong></span> or <span class=
          "keycap"><strong>Shift</strong></span>+<span class=
          "keycap"><strong>Up</strong></span> (<span class=
          "keycap"><strong>Down</strong></span> and <span class=
          "keycap"><strong>Up</strong></span> are the arrow
          keys).</p>
          <p>A right-click menu in the text area allows switching
          between displaying the main text or the contents of
          fields associated to the document (ie: author, abtract,
          etc.). This is especially useful in cases where the term
          match did not occur in the main text but in one of the
          fields. In the case of images, you can switch between
          three displays: the image itself, the image metadata as
          extracted by <span class=
          "command"><strong>exiftool</strong></span> and the
          fields, which is the metadata stored in the index.</p>
          <p>You can print the current preview window contents by
          typing <span class=
          "keycap"><strong>Ctrl-P</strong></span> (<span class=
          "keycap"><strong>Ctrl</strong></span> + <span class=
          "keycap"><strong>P</strong></span>) in the window
          text.</p>
          <div class="sect3">
            <div class="titlepage">
              <div>
                <div>
                  <h4 class="title"><a name=
                  "RCL.SEARCH.GUI.PREVIEW.SEARCH" id=
                  "RCL.SEARCH.GUI.PREVIEW.SEARCH"></a>3.1.6.1.&nbsp;Searching
                  inside the preview</h4>
                </div>
              </div>
            </div>
            <p>The preview window has an internal search
            capability, mostly controlled by the panel at the
            bottom of the window, which works in two modes: as a
            classical editor incremental search, where we look for
            the text entered in the entry zone, or as a way to walk
            the matches between the document and the <span class=
            "application">Recoll</span> query that found it.</p>
            <div class="variablelist">
              <dl class="variablelist">
                <dt><span class="term">Incremental text
                search</span></dt>
                <dd>
                  <p>The preview tabs have an internal incremental
                  search function. You initiate the search either
                  by typing a <span class=
                  "keycap"><strong>/</strong></span> (slash) or
                  <span class=
                  "keycap"><strong>CTL-F</strong></span> inside the
                  text area or by clicking into the <span class=
                  "guilabel">Search for:</span> text field and
                  entering the search string. You can then use the
                  <span class="guilabel">Next</span> and
                  <span class="guilabel">Previous</span> buttons to
                  find the next/previous occurrence. You can also
                  type <span class=
                  "keycap"><strong>F3</strong></span> inside the
                  text area to get to the next occurrence.</p>
                  <p>If you have a search string entered and you
                  use Ctrl-Up/Ctrl-Down to browse the results, the
                  search is initiated for each successive document.
                  If the string is found, the cursor will be
                  positioned at the first occurrence of the search
                  string.</p>
                </dd>
                <dt><span class="term">Walking the match
                lists</span></dt>
                <dd>
                  <p>If the entry area is empty when you click the
                  <span class="guilabel">Next</span> or
                  <span class="guilabel">Previous</span> buttons,
                  the editor will be scrolled to show the next
                  match to any search term (the next highlighted
                  zone). If you select a search group from the
                  dropdown list and click <span class=
                  "guilabel">Next</span> or <span class=
                  "guilabel">Previous</span>, the match list for
                  this group will be walked. This is not the same
                  as a text search, because the occurences will
                  include non-exact matches (as caused by stemming
                  or wildcards). The search will revert to the text
                  mode as soon as you edit the entry area.</p>
                </dd>
              </dl>
            </div>
          </div>
        </div>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name="RCL.SEARCH.GUI.FRAGBUTS"
                id="RCL.SEARCH.GUI.FRAGBUTS"></a>3.1.7.&nbsp;The
                Query Fragments window</h3>
              </div>
            </div>
          </div>
          <p>Selecting the <span class="guimenu">Tools</span> →
          <span class="guimenuitem">Query Fragments</span> menu
          entry will open a window with radio- and check-buttons
          which can be used to activate query language fragments
          for filtering the current query. This can be useful if
          you have frequent reusable selectors, for example,
          filtering on alternate directories, or searching just one
          category of files, not covered by the standard category
          selectors.</p>
          <p>The contents of the window are entirely customizable,
          and defined by the contents of the <code class=
          "filename">fragbuts.xml</code> file inside the
          configuration directory. The sample file distributed with
          <span class="application">Recoll</span> (which you should
          be able to find under <code class=
          "filename">/usr/share/recoll/examples/fragbuts.xml</code>),
          contains an example which filters the results from the
          WEB history.</p>
          <p>Here follows an example:</p>
          <pre class="programlisting">
          &lt;?xml version="1.0" encoding="UTF-8"?&gt;

          &lt;fragbuts version="1.0"&gt;

          &lt;radiobuttons&gt;

          &lt;fragbut&gt;
          &lt;label&gt;Include Web Results&lt;/label&gt;
          &lt;frag&gt;&lt;/frag&gt;
          &lt;/fragbut&gt;

          &lt;fragbut&gt;
          &lt;label&gt;Exclude Web Results&lt;/label&gt;
          &lt;frag&gt;-rclbes:BGL&lt;/frag&gt;
          &lt;/fragbut&gt;

          &lt;fragbut&gt;
          &lt;label&gt;Only Web Results&lt;/label&gt;
          &lt;frag&gt;rclbes:BGL&lt;/frag&gt;
          &lt;/fragbut&gt;

          &lt;/radiobuttons&gt;

          &lt;buttons&gt;

          &lt;fragbut&gt;
          &lt;label&gt;Year 2010&lt;/label&gt;
          &lt;frag&gt;date:2010-01-01/2010-12-31&lt;/frag&gt;
          &lt;/fragbut&gt;

          &lt;fragbut&gt;
          &lt;label&gt;My Great Directory Only&lt;/label&gt;
          &lt;frag&gt;dir:/my/great/directory&lt;/frag&gt;
          &lt;/fragbut&gt;

          &lt;/buttons&gt;
          &lt;/fragbuts&gt;
        </pre>
          <p>Each <code class="literal">radiobuttons</code> or
          <code class="literal">buttons</code> section defines a
          line of checkbuttons or radiobuttons inside the window.
          Any number of buttons can be selected, but the
          radiobuttons in a line are exclusive.</p>
          <p>Each <code class="literal">fragbut</code> section
          defines the label for a button, and the Query Language
          fragment which will be added (as an AND filter) before
          performing the query if the button is active.</p>
          <p>This feature is new in <span class=
          "application">Recoll</span> 1.20, and will probably be
          refined depending on user feedback.</p>
        </div>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name="RCL.SEARCH.GUI.COMPLEX"
                id=
                "RCL.SEARCH.GUI.COMPLEX"></a>3.1.8.&nbsp;Complex/advanced
                search</h3>
              </div>
            </div>
          </div>
          <p>The advanced search dialog helps you build more
          complex queries without memorizing the search language
          constructs. It can be opened through the <span class=
          "guilabel">Tools</span> menu or through the main
          toolbar.</p>
          <p><span class="application">Recoll</span> keeps a
          history of searches. See <a class="link" href=
          "#RCL.SEARCH.GUI.COMPLEX.HISTORY" title=
          "3.1.8.3.&nbsp;Avanced search history">Advanced search
          history</a>.</p>
          <p>The dialog has two tabs:</p>
          <div class="orderedlist">
            <ol class="orderedlist" type="1">
              <li class="listitem">
                <p>The first tab lets you specify terms to search
                for, and permits specifying multiple clauses which
                are combined to build the search.</p>
              </li>
              <li class="listitem">
                <p>The second tab lets filter the results according
                to file size, date of modification, MIME type, or
                location.</p>
              </li>
            </ol>
          </div>
          <p>Click on the <span class="guilabel">Start
          Search</span> button in the advanced search dialog, or
          type <span class="keycap"><strong>Enter</strong></span>
          in any text field to start the search. The button in the
          main window always performs a simple search.</p>
          <p>Click on the <code class="literal">Show query
          details</code> link at the top of the result page to see
          the query expansion.</p>
          <div class="sect3">
            <div class="titlepage">
              <div>
                <div>
                  <h4 class="title"><a name=
                  "RCL.SEARCH.GUI.COMPLEX.TERMS" id=
                  "RCL.SEARCH.GUI.COMPLEX.TERMS"></a>3.1.8.1.&nbsp;Avanced
                  search: the "find" tab</h4>
                </div>
              </div>
            </div>
            <p>This part of the dialog lets you constructc a query
            by combining multiple clauses of different types. Each
            entry field is configurable for the following
            modes:</p>
            <div class="itemizedlist">
              <ul class="itemizedlist" style=
              "list-style-type: disc;">
                <li class="listitem">
                  <p>All terms.</p>
                </li>
                <li class="listitem">
                  <p>Any term.</p>
                </li>
                <li class="listitem">
                  <p>None of the terms.</p>
                </li>
                <li class="listitem">
                  <p>Phrase (exact terms in order within an
                  adjustable window).</p>
                </li>
                <li class="listitem">
                  <p>Proximity (terms in any order within an
                  adjustable window).</p>
                </li>
                <li class="listitem">
                  <p>Filename search.</p>
                </li>
              </ul>
            </div>
            <p>Additional entry fields can be created by clicking
            the <span class="guilabel">Add clause</span>
            button.</p>
            <p>When searching, the non-empty clauses will be
            combined either with an AND or an OR conjunction,
            depending on the choice made on the left (<span class=
            "guilabel">All clauses</span> or <span class=
            "guilabel">Any clause</span>).</p>
            <p>Entries of all types except "Phrase" and "Near"
            accept a mix of single words and phrases enclosed in
            double quotes. Stemming and wildcard expansion will be
            performed as for simple search.</p>
            <p><b>Phrases and Proximity searches.&nbsp;</b>These
            two clauses work in similar ways, with the difference
            that proximity searches do not impose an order on the
            words. In both cases, an adjustable number (slack) of
            non-matched words may be accepted between the searched
            ones (use the counter on the left to adjust this
            count). For phrases, the default count is zero (exact
            match). For proximity it is ten (meaning that two
            search terms, would be matched if found within a window
            of twelve words). Examples: a phrase search for
            <code class="literal">quick fox</code> with a slack of
            0 will match <code class="literal">quick fox</code> but
            not <code class="literal">quick brown fox</code>. With
            a slack of 1 it will match the latter, but not
            <code class="literal">fox quick</code>. A proximity
            search for <code class="literal">quick fox</code> with
            the default slack will match the latter, and also
            <code class="literal">a fox is a cunning and quick
            animal</code>.</p>
          </div>
          <div class="sect3">
            <div class="titlepage">
              <div>
                <div>
                  <h4 class="title"><a name=
                  "RCL.SEARCH.GUI.COMPLEX.FILTER" id=
                  "RCL.SEARCH.GUI.COMPLEX.FILTER"></a>3.1.8.2.&nbsp;Avanced
                  search: the "filter" tab</h4>
                </div>
              </div>
            </div>
            <p>This part of the dialog has several sections which
            allow filtering the results of a search according to a
            number of criteria</p>
            <div class="itemizedlist">
              <ul class="itemizedlist" style=
              "list-style-type: disc;">
                <li class="listitem">
                  <p>The first section allows filtering by dates of
                  last modification. You can specify both a minimum
                  and a maximum date. The initial values are set
                  according to the oldest and newest documents
                  found in the index.</p>
                </li>
                <li class="listitem">
                  <p>The next section allows filtering the results
                  by file size. There are two entries for minimum
                  and maximum size. Enter decimal numbers. You can
                  use suffix multipliers: <code class=
                  "literal">k/K</code>, <code class=
                  "literal">m/M</code>, <code class=
                  "literal">g/G</code>, <code class=
                  "literal">t/T</code> for 1E3, 1E6, 1E9, 1E12
                  respectively.</p>
                </li>
                <li class="listitem">
                  <p>The next section allows filtering the results
                  by their MIME types, or MIME categories (ie:
                  media/text/message/etc.).</p>
                  <p>You can transfer the types between two boxes,
                  to define which will be included or excluded by
                  the search.</p>
                  <p>The state of the file type selection can be
                  saved as the default (the file type filter will
                  not be activated at program start-up, but the
                  lists will be in the restored state).</p>
                </li>
                <li class="listitem">
                  <p>The bottom section allows restricting the
                  search results to a sub-tree of the indexed area.
                  You can use the <span class=
                  "guilabel">Invert</span> checkbox to search for
                  files not in the sub-tree instead. If you use
                  directory filtering often and on big subsets of
                  the file system, you may think of setting up
                  multiple indexes instead, as the performance may
                  be better.</p>
                  <p>You can use relative/partial paths for
                  filtering. Ie, entering <code class=
                  "literal">dirA/dirB</code> would match either
                  <code class=
                  "filename">/dir1/dirA/dirB/myfile1</code> or
                  <code class=
                  "filename">/dir2/dirA/dirB/someother/myfile2</code>.</p>
                </li>
              </ul>
            </div>
          </div>
          <div class="sect3">
            <div class="titlepage">
              <div>
                <div>
                  <h4 class="title"><a name=
                  "RCL.SEARCH.GUI.COMPLEX.HISTORY" id=
                  "RCL.SEARCH.GUI.COMPLEX.HISTORY"></a>3.1.8.3.&nbsp;Avanced
                  search history</h4>
                </div>
              </div>
            </div>
            <p>The advanced search tool memorizes the last 100
            searches performed. You can walk the saved searches by
            using the up and down arrow keys while the keyboard
            focus belongs to the advanced search dialog.</p>
            <p>The complex search history can be erased, along with
            the one for simple search, by selecting the
            <span class="guimenu">File</span> → <span class=
            "guimenuitem">Erase Search History</span> menu
            entry.</p>
          </div>
        </div>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name=
                "RCL.SEARCH.GUI.TERMEXPLORER" id=
                "RCL.SEARCH.GUI.TERMEXPLORER"></a>3.1.9.&nbsp;The
                term explorer tool</h3>
              </div>
            </div>
          </div>
          <p><span class="application">Recoll</span> automatically
          manages the expansion of search terms to their
          derivatives (ie: plural/singular, verb inflections). But
          there are other cases where the exact search term is not
          known. For example, you may not remember the exact
          spelling, or only know the beginning of the name.</p>
          <p>The search will only propose replacement terms with
          spelling variations when no matching document were found.
          In some cases, both proper spellings and mispellings are
          present in the index, and it may be interesting to look
          for them explicitely.</p>
          <p>The term explorer tool (started from the toolbar icon
          or from the <span class="guilabel">Term explorer</span>
          entry of the <span class="guilabel">Tools</span> menu)
          can be used to search the full index terms list. It has
          three modes of operations:</p>
          <div class="variablelist">
            <dl class="variablelist">
              <dt><span class="term">Wildcard</span></dt>
              <dd>
                <p>In this mode of operation, you can enter a
                search string with shell-like wildcards (*, ?, []).
                ie: <em class="replaceable"><code>xapi*</code></em>
                would display all index terms beginning with
                <em class="replaceable"><code>xapi</code></em>.
                (More about wildcards <a class="link" href=
                "#RCL.SEARCH.WILDCARDS" title=
                "3.8.1.&nbsp;More about wildcards">here</a>).</p>
              </dd>
              <dt><span class="term">Regular expression</span></dt>
              <dd>
                <p>This mode will accept a regular expression as
                input. Example: <em class=
                "replaceable"><code>word[0-9]+</code></em>. The
                expression is implicitely anchored at the
                beginning. Ie: <em class=
                "replaceable"><code>press</code></em> will match
                <em class="replaceable"><code>pression</code></em>
                but not <em class=
                "replaceable"><code>expression</code></em>. You can
                use <em class=
                "replaceable"><code>.*press</code></em> to match
                the latter, but be aware that this will cause a
                full index term list scan, which can be quite
                long.</p>
              </dd>
              <dt><span class="term">Stem expansion</span></dt>
              <dd>
                <p>This mode will perform the usual stem expansion
                normally done as part user input processing. As
                such it is probably mostly useful to demonstrate
                the process.</p>
              </dd>
              <dt><span class="term">Spelling/Phonetic</span></dt>
              <dd>
                <p>In this mode, you enter the term as you think it
                is spelled, and <span class=
                "application">Recoll</span> will do its best to
                find index terms that sound like your entry. This
                mode uses the <span class=
                "application">Aspell</span> spelling application,
                which must be installed on your system for things
                to work (if your documents contain non-ascii
                characters, <span class="application">Recoll</span>
                needs an aspell version newer than 0.60 for UTF-8
                support). The language which is used to build the
                dictionary out of the index terms (which is done at
                the end of an indexing pass) is the one defined by
                your NLS environment. Weird things will probably
                happen if languages are mixed up.</p>
              </dd>
            </dl>
          </div>
          <p>Note that in cases where <span class=
          "application">Recoll</span> does not know the beginning
          of the string to search for (ie a wildcard expression
          like <em class="replaceable"><code>*coll</code></em>),
          the expansion can take quite a long time because the full
          index term list will have to be processed. The expansion
          is currently limited at 10000 results for wildcards and
          regular expressions. It is possible to change the limit
          in the configuration file.</p>
          <p>Double-clicking on a term in the result list will
          insert it into the simple search entry field. You can
          also cut/paste between the result list and any entry
          field (the end of lines will be taken care of).</p>
        </div>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name="RCL.SEARCH.GUI.MULTIDB"
                id=
                "RCL.SEARCH.GUI.MULTIDB"></a>3.1.10.&nbsp;Multiple
                indexes</h3>
              </div>
            </div>
          </div>
          <p>See the <a class="link" href=
          "#RCL.INDEXING.CONFIG.MULTIPLE" title=
          "2.3.1.&nbsp;Multiple indexes">section describing the use
          of multiple indexes</a> for generalities. Only the
          aspects concerning the <span class=
          "command"><strong>recoll</strong></span> GUI are
          described here.</p>
          <p>A <span class="command"><strong>recoll</strong></span>
          program instance is always associated with a specific
          index, which is the one to be updated when requested from
          the <span class="guimenu">File</span> menu, but it can
          use any number of <span class="application">Recoll</span>
          indexes for searching. The external indexes can be
          selected through the <span class="guilabel">external
          indexes</span> tab in the preferences dialog.</p>
          <p>Index selection is performed in two phases. A set of
          all usable indexes must first be defined, and then the
          subset of indexes to be used for searching. These
          parameters are retained across program executions (there
          are kept separately for each <span class=
          "application">Recoll</span> configuration). The set of
          all indexes is usually quite stable, while the active
          ones might typically be adjusted quite frequently.</p>
          <p>The main index (defined by <code class=
          "envar">RECOLL_CONFDIR</code>) is always active. If this
          is undesirable, you can set up your base configuration to
          index an empty directory.</p>
          <p>When adding a new index to the set, you can select
          either a <span class="application">Recoll</span>
          configuration directory, or directly a <span class=
          "application">Xapian</span> index directory. In the first
          case, the <span class="application">Xapian</span> index
          directory will be obtained from the selected
          configuration.</p>
          <p>As building the set of all indexes can be a little
          tedious when done through the user interface, you can use
          the <code class="envar">RECOLL_EXTRA_DBS</code>
          environment variable to provide an initial set. This
          might typically be set up by a system administrator so
          that every user does not have to do it. The variable
          should define a colon-separated list of index
          directories, ie:</p>
          <pre class="screen">
          export RECOLL_EXTRA_DBS=/some/place/xapiandb:/some/other/db</pre>
          <p>Another environment variable, <code class=
          "envar">RECOLL_ACTIVE_EXTRA_DBS</code> allows adding to
          the active list of indexes. This variable was suggested
          and implemented by a <span class=
          "application">Recoll</span> user. It is mostly useful if
          you use scripts to mount external volumes with
          <span class="application">Recoll</span> indexes. By using
          <code class="envar">RECOLL_EXTRA_DBS</code> and
          <code class="envar">RECOLL_ACTIVE_EXTRA_DBS</code>, you
          can add and activate the index for the mounted volume
          when starting <span class=
          "command"><strong>recoll</strong></span>.</p>
          <p><code class="envar">RECOLL_ACTIVE_EXTRA_DBS</code> is
          available for <span class="application">Recoll</span>
          versions 1.17.2 and later. A change was made in the same
          update so that <span class=
          "command"><strong>recoll</strong></span> will
          automatically deactivate unreachable indexes when
          starting up.</p>
        </div>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name="RCL.SEARCH.GUI.HISTORY"
                id=
                "RCL.SEARCH.GUI.HISTORY"></a>3.1.11.&nbsp;Document
                history</h3>
              </div>
            </div>
          </div>
          <p>Documents that you actually view (with the internal
          preview or an external tool) are entered into the
          document history, which is remembered.</p>
          <p>You can display the history list by using the
          <span class="guilabel">Tools/</span><span class=
          "guilabel">Doc History</span> menu entry.</p>
          <p>You can erase the document history by using the
          <span class="guilabel">Erase document history</span>
          entry in the <span class="guimenu">File</span> menu.</p>
        </div>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name="RCL.SEARCH.GUI.SORT" id=
                "RCL.SEARCH.GUI.SORT"></a>3.1.12.&nbsp;Sorting
                search results and collapsing duplicates</h3>
              </div>
            </div>
          </div>
          <p>The documents in a result list are normally sorted in
          order of relevance. It is possible to specify a different
          sort order, either by using the vertical arrows in the
          GUI toolbox to sort by date, or switching to the result
          table display and clicking on any header. The sort order
          chosen inside the result table remains active if you
          switch back to the result list, until you click one of
          the vertical arrows, until both are unchecked (you are
          back to sort by relevance).</p>
          <p>Sort parameters are remembered between program
          invocations, but result sorting is normally always
          inactive when the program starts. It is possible to keep
          the sorting activation state between program invocations
          by checking the <span class="guilabel">Remember sort
          activation state</span> option in the preferences.</p>
          <p>It is also possible to hide duplicate entries inside
          the result list (documents with the exact same contents
          as the displayed one). The test of identity is based on
          an MD5 hash of the document container, not only of the
          text contents (so that ie, a text document with an image
          added will not be a duplicate of the text only).
          Duplicates hiding is controlled by an entry in the
          <span class="guilabel">GUI configuration</span> dialog,
          and is off by default.</p>
          <p>As of release 1.19, when a result document does have
          undisplayed duplicates, a <code class=
          "literal">Dups</code> link will be shown with the result
          list entry. Clicking the link will display the paths
          (URLs + ipaths) for the duplicate entries.</p>
        </div>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name="RCL.SEARCH.GUI.TIPS" id=
                "RCL.SEARCH.GUI.TIPS"></a>3.1.13.&nbsp;Search tips,
                shortcuts</h3>
              </div>
            </div>
          </div>
          <div class="sect3">
            <div class="titlepage">
              <div>
                <div>
                  <h4 class="title"><a name=
                  "RCL.SEARCH.GUI.TIPS.TERMS" id=
                  "RCL.SEARCH.GUI.TIPS.TERMS"></a>3.1.13.1.&nbsp;Terms
                  and search expansion</h4>
                </div>
              </div>
            </div>
            <p><b>Term completion.&nbsp;</b>Typing <span class=
            "keycap"><strong>Esc</strong></span> <span class=
            "keycap"><strong>Space</strong></span> in the simple
            search entry field while entering a word will either
            complete the current word if its beginning matches a
            unique term in the index, or open a window to propose a
            list of completions.</p>
            <p><b>Picking up new terms from result or preview
            text.&nbsp;</b>Double-clicking on a word in the result
            list or in a preview window will copy it to the simple
            search entry field.</p>
            <p><b>Wildcards.&nbsp;</b>Wildcards can be used inside
            search terms in all forms of searches. <a class="link"
            href="#RCL.SEARCH.WILDCARDS" title=
            "3.8.1.&nbsp;More about wildcards">More about
            wildcards</a>.</p>
            <p><b>Automatic suffixes.&nbsp;</b>Words like
            <code class="literal">odt</code> or <code class=
            "literal">ods</code> can be automatically turned into
            query language <code class="literal">ext:xxx</code>
            clauses. This can be enabled in the <span class=
            "guilabel">Search preferences</span> panel in the
            GUI.</p>
            <p><b>Disabling stem expansion.&nbsp;</b>Entering a
            capitalized word in any search field will prevent stem
            expansion (no search for <code class=
            "literal">gardening</code> if you enter <code class=
            "literal">Garden</code> instead of <code class=
            "literal">garden</code>). This is the only case where
            character case should make a difference for a
            <span class="application">Recoll</span> search. You can
            also disable stem expansion or change the stemming
            language in the preferences.</p>
            <p><b>Finding related documents.&nbsp;</b>Selecting the
            <span class="guilabel">Find similar documents</span>
            entry in the result list paragraph right-click menu
            will select a set of "interesting" terms from the
            current result, and insert them into the simple search
            entry field. You can then possibly edit the list and
            start a search to find documents which may be
            apparented to the current result.</p>
            <p><b>File names.&nbsp;</b>File names are added as
            terms during indexing, and you can specify them as
            ordinary terms in normal search fields (<span class=
            "application">Recoll</span> used to index all
            directories in the file path as terms. This has been
            abandoned as it did not seem really useful).
            Alternatively, you can use the specific file name
            search which will <span class=
            "emphasis"><em>only</em></span> look for file names,
            and may be faster than the generic search especially
            when using wildcards.</p>
          </div>
          <div class="sect3">
            <div class="titlepage">
              <div>
                <div>
                  <h4 class="title"><a name=
                  "RCL.SEARCH.GUI.TIPS.PHRASES" id=
                  "RCL.SEARCH.GUI.TIPS.PHRASES"></a>3.1.13.2.&nbsp;Working
                  with phrases and proximity</h4>
                </div>
              </div>
            </div>
            <p><b>Phrases and Proximity searches.&nbsp;</b>A phrase
            can be looked for by enclosing it in double quotes.
            Example: <code class="literal">"user manual"</code>
            will look only for occurrences of <code class=
            "literal">user</code> immediately followed by
            <code class="literal">manual</code>. You can use the
            <span class="guilabel">This phrase</span> field of the
            advanced search dialog to the same effect. Phrases can
            be entered along simple terms in all simple or advanced
            search entry fields (except <span class="guilabel">This
            exact phrase</span>).</p>
            <p><b>AutoPhrases.&nbsp;</b>This option can be set in
            the preferences dialog. If it is set, a phrase will be
            automatically built and added to simple searches when
            looking for <code class="literal">Any terms</code>.
            This will not change radically the results, but will
            give a relevance boost to the results where the search
            terms appear as a phrase. Ie: searching for
            <code class="literal">virtual reality</code> will still
            find all documents where either <code class=
            "literal">virtual</code> or <code class=
            "literal">reality</code> or both appear, but those
            which contain <code class="literal">virtual
            reality</code> should appear sooner in the list.</p>
            <p>Phrase searches can strongly slow down a query if
            most of the terms in the phrase are common. This is why
            the <code class="varname">autophrase</code> option is
            off by default for <span class=
            "application">Recoll</span> versions before 1.17. As of
            version 1.17, <code class="varname">autophrase</code>
            is on by default, but very common terms will be removed
            from the constructed phrase. The removal threshold can
            be adjusted from the search preferences.</p>
            <p><b>Phrases and abbreviations.&nbsp;</b>As of
            <span class="application">Recoll</span> version 1.17,
            dotted abbreviations like <code class=
            "literal">I.B.M.</code> are also automatically indexed
            as a word without the dots: <code class=
            "literal">IBM</code>. Searching for the word inside a
            phrase (ie: <code class="literal">"the IBM
            company"</code>) will only match the dotted
            abrreviation if you increase the phrase slack (using
            the advanced search panel control, or the <code class=
            "literal">o</code> query language modifier). Literal
            occurences of the word will be matched normally.</p>
          </div>
          <div class="sect3">
            <div class="titlepage">
              <div>
                <div>
                  <h4 class="title"><a name=
                  "RCL.SEARCH.GUI.TIPS.MISC" id=
                  "RCL.SEARCH.GUI.TIPS.MISC"></a>3.1.13.3.&nbsp;Others</h4>
                </div>
              </div>
            </div>
            <p><b>Using fields.&nbsp;</b>You can use the <a class=
            "link" href="#RCL.SEARCH.LANG" title=
            "3.6.&nbsp;The query language">query language</a> and
            field specifications to only search certain parts of
            documents. This can be especially helpful with email,
            for example only searching emails from a specific
            originator: <code class="literal">search tips
            from:helpfulgui</code></p>
            <p><b>Ajusting the result table columns.&nbsp;</b>When
            displaying results in table mode, you can use a right
            click on the table headers to activate a pop-up menu
            which will let you adjust what columns are displayed.
            You can drag the column headers to adjust their order.
            You can click them to sort by the field displayed in
            the column. You can also save the result list in CSV
            format.</p>
            <p><b>Changing the GUI geometry.&nbsp;</b>It is
            possible to configure the GUI in wide form factor by
            dragging the toolbars to one of the sides (their
            location is remembered between sessions), and moving
            the category filters to a menu (can be set in the
            <span class="guimenu">Preferences</span> → <span class=
            "guimenuitem">GUI configuration</span> → <span class=
            "guimenuitem">User interface</span> panel).</p>
            <p><b>Query explanation.&nbsp;</b>You can get an exact
            description of what the query looked for, including
            stem expansion, and Boolean operators used, by clicking
            on the result list header.</p>
            <p><b>Advanced search history.&nbsp;</b>As of
            <span class="application">Recoll</span> 1.18, you can
            display any of the last 100 complex searches performed
            by using the up and down arrow keys while the advanced
            search panel is active.</p>
            <p><b>Browsing the result list inside a preview
            window.&nbsp;</b>Entering <span class=
            "keycap"><strong>Shift-Down</strong></span> or
            <span class="keycap"><strong>Shift-Up</strong></span>
            (<span class="keycap"><strong>Shift</strong></span> +
            an arrow key) in a preview window will display the next
            or the previous document from the result list. Any
            secondary search currently active will be executed on
            the new document.</p>
            <p><b>Scrolling the result list from the
            keyboard.&nbsp;</b>You can use <span class=
            "keycap"><strong>PageUp</strong></span> and
            <span class="keycap"><strong>PageDown</strong></span>
            to scroll the result list, <span class=
            "keycap"><strong>Shift+Home</strong></span> to go back
            to the first page. These work even while the focus is
            in the search entry.</p>
            <p><b>Result table: moving the focus to the
            table.&nbsp;</b>You can use <span class=
            "keycap"><strong>Ctrl-r</strong></span> to move the
            focus from the search entry to the table, and then use
            the arrow keys to change the current row. <span class=
            "keycap"><strong>Ctrl-Shift-s</strong></span> returns
            to the search.</p>
            <p><b>Result table: open / preview.&nbsp;</b>With the
            focus in the result table, you can use <span class=
            "keycap"><strong>Ctrl-o</strong></span> to open the
            document from the current row, <span class=
            "keycap"><strong>Ctrl-Shift-o</strong></span> to open
            the document and close <span class=
            "command"><strong>recoll</strong></span>, <span class=
            "keycap"><strong>Ctrl-d</strong></span> to preview the
            document.</p>
            <p><b>Editing a new search while the focus is not in
            the search entry.&nbsp;</b>You can use the <span class=
            "keycap"><strong>Ctrl-Shift-S</strong></span> shortcut
            to return the cursor to the search entry (and select
            the current search text), while the focus is anywhere
            in the main window.</p>
            <p><b>Forced opening of a preview window.&nbsp;</b>You
            can use <span class=
            "keycap"><strong>Shift</strong></span>+Click on a
            result list <code class="literal">Preview</code> link
            to force the creation of a preview window instead of a
            new tab in the existing one.</p>
            <p><b>Closing previews.&nbsp;</b>Entering <span class=
            "keycap"><strong>Ctrl-W</strong></span> in a tab will
            close it (and, for the last tab, close the preview
            window). Entering <span class=
            "keycap"><strong>Esc</strong></span> will close the
            preview window and all its tabs.</p>
            <p><b>Printing previews.&nbsp;</b>Entering <span class=
            "keycap"><strong>Ctrl-P</strong></span> in a preview
            window will print the currently displayed text.</p>
            <p><b>Quitting.&nbsp;</b>Entering <span class=
            "keycap"><strong>Ctrl-Q</strong></span> almost anywhere
            will close the application.</p>
          </div>
        </div>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name="RCL.SEARCH.SAVING" id=
                "RCL.SEARCH.SAVING"></a>3.1.14.&nbsp;Saving and
                restoring queries (1.21 and later)</h3>
              </div>
            </div>
          </div>
          <p>Both simple and advanced query dialogs save recent
          history, but the amount is limited: old queries will
          eventually be forgotten. Also, important queries may be
          difficult to find among others. This is why both types of
          queries can also be explicitely saved to files, from the
          GUI menus: <span class="guimenu">File</span> →
          <span class="guimenuitem">Save last query / Load last
          query</span></p>
          <p>The default location for saved queries is a
          subdirectory of the current configuration directory, but
          saved queries are ordinary files and can be written or
          moved anywhere.</p>
          <p>Some of the saved query parameters are part of the
          preferences (e.g. <code class="literal">autophrase</code>
          or the active external indexes), and may differ when the
          query is loaded from the time it was saved. In this case,
          <span class="application">Recoll</span> will warn of the
          differences, but will not change the user
          preferences.</p>
        </div>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name="RCL.SEARCH.GUI.CUSTOM"
                id=
                "RCL.SEARCH.GUI.CUSTOM"></a>3.1.15.&nbsp;Customizing
                the search interface</h3>
              </div>
            </div>
          </div>
          <p>You can customize some aspects of the search interface
          by using the <span class="guimenu">GUI
          configuration</span> entry in the <span class=
          "guimenu">Preferences</span> menu.</p>
          <p>There are several tabs in the dialog, dealing with the
          interface itself, the parameters used for searching and
          returning results, and what indexes are searched.</p>
          <p><a name="RCL.SEARCH.GUI.CUSTOM.UI" id=
          "RCL.SEARCH.GUI.CUSTOM.UI"></a><b>User interface
          parameters:&nbsp;</b></p>
          <div class="itemizedlist">
            <ul class="itemizedlist" style=
            "list-style-type: disc;">
              <li class="listitem">
                <p><span class="guilabel">Highlight color for query
                terms</span>: Terms from the user query are
                highlighted in the result list samples and the
                preview window. The color can be chosen here. Any
                Qt color string should work (ie <code class=
                "literal">red</code>, <code class=
                "literal">#ff0000</code>). The default is
                <code class="literal">blue</code>.</p>
              </li>
              <li class="listitem">
                <p><span class="guilabel">Style sheet</span>: The
                name of a <span class="application">Qt</span> style
                sheet text file which is applied to the whole
                Recoll application on startup. The default value is
                empty, but there is a skeleton style sheet
                (<code class="filename">recoll.qss</code>) inside
                the <code class=
                "filename">/usr/share/recoll/examples</code>
                directory. Using a style sheet, you can change most
                <span class=
                "command"><strong>recoll</strong></span> graphical
                parameters: colors, fonts, etc. See the sample file
                for a few simple examples.</p>
                <p>You should be aware that parameters (e.g.: the
                background color) set inside the <span class=
                "application">Recoll</span> GUI style sheet will
                override global system preferences, with possible
                strange side effects: for example if you set the
                foreground to a light color and the background to a
                dark one in the desktop preferences, but only the
                background is set inside the <span class=
                "application">Recoll</span> style sheet, and it is
                light too, then text will appear light-on-light
                inside the <span class="application">Recoll</span>
                GUI.</p>
              </li>
              <li class="listitem">
                <p><span class="guilabel">Maximum text size
                highlighted for preview</span> Inserting highlights
                on search term inside the text before inserting it
                in the preview window involves quite a lot of
                processing, and can be disabled over the given text
                size to speed up loading.</p>
              </li>
              <li class="listitem">
                <p><span class="guilabel">Prefer HTML to plain text
                for preview</span> if set, Recoll will display HTML
                as such inside the preview window. If this causes
                problems with the Qt HTML display, you can uncheck
                it to display the plain text version instead.</p>
              </li>
              <li class="listitem">
                <p><span class="guilabel">Activate links in
                preview</span> if set, Recoll will turn HTTP links
                found inside plain text into proper HTML anchors,
                and clicking a link inside a preview window will
                start the default browser on the link target.</p>
              </li>
              <li class="listitem">
                <p><span class="guilabel">Plain text to HTML line
                style</span>: when displaying plain text inside the
                preview window, <span class=
                "application">Recoll</span> tries to preserve some
                of the original text line breaks and indentation.
                It can either use PRE HTML tags, which will well
                preserve the indentation but will force horizontal
                scrolling for long lines, or use BR tags to break
                at the original line breaks, which will let the
                editor introduce other line breaks according to the
                window width, but will lose some of the original
                indentation. The third option has been available in
                recent releases and is probably now the best one:
                use PRE tags with line wrapping.</p>
              </li>
              <li class="listitem">
                <p><span class="guilabel">Choose editor
                application</span>: this opens a dialog which
                allows you to select the application to be used to
                open each MIME type. The default is to use the
                <span class=
                "command"><strong>xdg-open</strong></span> utility,
                but you can use this dialog to override it, setting
                exceptions for MIME types that will still be opened
                according to <span class=
                "application">Recoll</span> preferences. This is
                useful for passing parameters like page numbers or
                search strings to applications that support them
                (e.g. <span class="application">evince</span>).
                This cannot be done with <span class=
                "command"><strong>xdg-open</strong></span> which
                only supports passing one parameter.</p>
              </li>
              <li class="listitem">
                <p><span class="guilabel">Disable Qt autocompletion
                in search entry</span>: this will disable the
                completion popup. Il will only appear, and display
                the full history, either if you enter only white
                space in the search area, or if you click the clock
                button on the right of the area.</p>
              </li>
              <li class="listitem">
                <p><span class="guilabel">Document filter choice
                style</span>: this will let you choose if the
                document categories are displayed as a list or a
                set of buttons, or a menu.</p>
              </li>
              <li class="listitem">
                <p><span class="guilabel">Start with simple search
                mode</span>: this lets you choose the value of the
                simple search type on program startup. Either a
                fixed value (e.g. <code class="literal">Query
                Language</code>, or the value in use when the
                program last exited.</p>
              </li>
              <li class="listitem">
                <p><span class="guilabel">Start with advanced
                search dialog open</span> : If you use this dialog
                frequently, checking the entries will get it to
                open when recoll starts.</p>
              </li>
              <li class="listitem">
                <p><span class="guilabel">Remember sort activation
                state</span> if set, Recoll will remember the sort
                tool stat between invocations. It normally starts
                with sorting disabled.</p>
              </li>
            </ul>
          </div>
          <p><a name="RCL.SEARCH.GUI.CUSTOM.RL" id=
          "RCL.SEARCH.GUI.CUSTOM.RL"></a><b>Result list
          parameters:&nbsp;</b></p>
          <div class="itemizedlist">
            <ul class="itemizedlist" style=
            "list-style-type: disc;">
              <li class="listitem">
                <p><span class="guilabel">Number of results in a
                result page</span></p>
              </li>
              <li class="listitem">
                <p><span class="guilabel">Result list font</span>:
                There is quite a lot of information shown in the
                result list, and you may want to customize the font
                and/or font size. The rest of the fonts used by
                <span class="application">Recoll</span> are
                determined by your generic Qt config (try the
                <span class=
                "command"><strong>qtconfig</strong></span>
                command).</p>
              </li>
              <li class="listitem">
                <p><a name="RCL.SEARCH.GUI.CUSTOM.RESULTPARA" id=
                "RCL.SEARCH.GUI.CUSTOM.RESULTPARA"></a><span class=
                "guilabel">Edit result list paragraph format
                string</span>: allows you to change the
                presentation of each result list entry. See the
                <a class="link" href=
                "#RCL.SEARCH.GUI.CUSTOM.RESLIST" title=
                "3.1.15.1.&nbsp;The result list format">result list
                customisation section</a>.</p>
              </li>
              <li class="listitem">
                <p><a name="RCL.SEARCH.GUI.CUSTOM.RESULTHEAD" id=
                "RCL.SEARCH.GUI.CUSTOM.RESULTHEAD"></a><span class=
                "guilabel">Edit result page HTML header
                insert</span>: allows you to define text inserted
                at the end of the result page HTML header. More
                detail in the <a class="link" href=
                "#RCL.SEARCH.GUI.CUSTOM.RESLIST" title=
                "3.1.15.1.&nbsp;The result list format">result list
                customisation section.</a></p>
              </li>
              <li class="listitem">
                <p><span class="guilabel">Date format</span>:
                allows specifying the format used for displaying
                dates inside the result list. This should be
                specified as an strftime() string (man
                strftime).</p>
              </li>
              <li class="listitem">
                <p><a name="RCL.SEARCH.GUI.CUSTOM.ABSSEP" id=
                "RCL.SEARCH.GUI.CUSTOM.ABSSEP"></a><span class=
                "guilabel">Abstract snippet separator</span>: for
                synthetic abstracts built from index data, which
                are usually made of several snippets from different
                parts of the document, this defines the snippet
                separator, an ellipsis by default.</p>
              </li>
            </ul>
          </div>
          <p><a name="RCL.SEARCH.GUI.CUSTOM.SEARCH" id=
          "RCL.SEARCH.GUI.CUSTOM.SEARCH"></a><b>Search
          parameters:&nbsp;</b></p>
          <div class="itemizedlist">
            <ul class="itemizedlist" style=
            "list-style-type: disc;">
              <li class="listitem">
                <p><span class="guilabel">Hide duplicate
                results</span>: decides if result list entries are
                shown for identical documents found in different
                places.</p>
              </li>
              <li class="listitem">
                <p><span class="guilabel">Stemming language</span>:
                stemming obviously depends on the document's
                language. This listbox will let you chose among the
                stemming databases which were built during indexing
                (this is set in the <a class="link" href=
                "#RCL.INSTALL.CONFIG.RECOLLCONF" title=
                "6.4.2.&nbsp;Recoll main configuration file, recoll.conf">
                main configuration file</a>), or later added with
                <span class="command"><strong>recollindex
                -s</strong></span> (See the recollindex manual).
                Stemming languages which are dynamically added will
                be deleted at the next indexing pass unless they
                are also added in the configuration file.</p>
              </li>
              <li class="listitem">
                <p><span class="guilabel">Automatically add phrase
                to simple searches</span>: a phrase will be
                automatically built and added to simple searches
                when looking for <code class="literal">Any
                terms</code>. This will give a relevance boost to
                the results where the search terms appear as a
                phrase (consecutive and in order).</p>
              </li>
              <li class="listitem">
                <p><span class="guilabel">Autophrase term frequency
                threshold percentage</span>: very frequent terms
                should not be included in automatic phrase searches
                for performance reasons. The parameter defines the
                cutoff percentage (percentage of the documents
                where the term appears).</p>
              </li>
              <li class="listitem">
                <p><span class="guilabel">Replace abstracts from
                documents</span>: this decides if we should
                synthesize and display an abstract in place of an
                explicit abstract found within the document
                itself.</p>
              </li>
              <li class="listitem">
                <p><span class="guilabel">Dynamically build
                abstracts</span>: this decides if <span class=
                "application">Recoll</span> tries to build document
                abstracts (lists of <span class=
                "emphasis"><em>snippets</em></span>) when
                displaying the result list. Abstracts are
                constructed by taking context from the document
                information, around the search terms.</p>
              </li>
              <li class="listitem">
                <p><span class="guilabel">Synthetic abstract
                size</span>: adjust to taste...</p>
              </li>
              <li class="listitem">
                <p><span class="guilabel">Synthetic abstract
                context words</span>: how many words should be
                displayed around each term occurrence.</p>
              </li>
              <li class="listitem">
                <p><span class="guilabel">Query language magic file
                name suffixes</span>: a list of words which
                automatically get turned into <code class=
                "literal">ext:xxx</code> file name suffix clauses
                when starting a query language query (ie:
                <code class="literal">doc xls xlsx...</code>). This
                will save some typing for people who use file types
                a lot when querying.</p>
              </li>
            </ul>
          </div>
          <p><a name="RCL.SEARCH.GUI.CUSTOM.EXTRADB" id=
          "RCL.SEARCH.GUI.CUSTOM.EXTRADB"></a><b>External
          indexes:&nbsp;</b>This panel will let you browse for
          additional indexes that you may want to search. External
          indexes are designated by their database directory (ie:
          <code class=
          "filename">/home/someothergui/.recoll/xapiandb</code>,
          <code class=
          "filename">/usr/local/recollglobal/xapiandb</code>).</p>
          <p>Once entered, the indexes will appear in the
          <span class="guilabel">External indexes</span> list, and
          you can chose which ones you want to use at any moment by
          checking or unchecking their entries.</p>
          <p>Your main database (the one the current configuration
          indexes to), is always implicitly active. If this is not
          desirable, you can set up your configuration so that it
          indexes, for example, an empty directory. An alternative
          indexer may also need to implement a way of purging the
          index from stale data,</p>
          <div class="sect3">
            <div class="titlepage">
              <div>
                <div>
                  <h4 class="title"><a name=
                  "RCL.SEARCH.GUI.CUSTOM.RESLIST" id=
                  "RCL.SEARCH.GUI.CUSTOM.RESLIST"></a>3.1.15.1.&nbsp;The
                  result list format</h4>
                </div>
              </div>
            </div>
            <p>Newer versions of Recoll (from 1.17) normally use
            WebKit HTML widgets for the result list and the
            <a class="link" href=
            "#RCL.SEARCH.GUI.RESULTLIST.MENU.SNIPPETS">snippets
            window</a> (this may be disabled at build time). Total
            customisation is possible with full support for CSS and
            Javascript. Conversely, there are limits to what you
            can do with the older Qt QTextBrowser, but still, it is
            possible to decide what data each result will contain,
            and how it will be displayed.</p>
            <p>The result list presentation can be exhaustively
            customized by adjusting two elements:</p>
            <div class="itemizedlist">
              <ul class="itemizedlist" style=
              "list-style-type: disc;">
                <li class="listitem">
                  <p>The paragraph format</p>
                </li>
                <li class="listitem">
                  <p>HTML code inside the header section. For
                  versions 1.21 and later, this is also used for
                  the <a class="link" href=
                  "#RCL.SEARCH.GUI.RESULTLIST.MENU.SNIPPETS">snippets
                  window</a></p>
                </li>
              </ul>
            </div>
            <p>The paragraph format and the header fragment can be
            edited from the <span class="guilabel">Result
            list</span> tab of the <span class="guilabel">GUI
            configuration</span>.</p>
            <p>The header fragment is used both for the result list
            and the snippets window. The snippets list is a table
            and has a <code class="literal">snippets</code> class
            attribute. Each paragraph in the result list is a
            table, with class <code class="literal">respar</code>,
            but this can be changed by editing the paragraph
            format.</p>
            <p>There are a few examples on the <a class="ulink"
            href="http://www.recoll.org/custom.html" target=
            "_top">page about customising the result list</a> on
            the <span class="application">Recoll</span> web
            site.</p>
            <div class="sect4">
              <div class="titlepage">
                <div>
                  <div>
                    <h5 class="title"><a name=
                    "RCL.SEARCH.GUI.CUSTOM.RESLIST.PARA" id=
                    "RCL.SEARCH.GUI.CUSTOM.RESLIST.PARA"></a>The
                    paragraph format</h5>
                  </div>
                </div>
              </div>
              <p>This is an arbitrary HTML string where the
              following printf-like <code class="literal">%</code>
              substitutions will be performed:</p>
              <div class="itemizedlist">
                <ul class="itemizedlist" style=
                "list-style-type: disc;">
                  <li class="listitem">
                    <p><b>%A.&nbsp;</b>Abstract</p>
                  </li>
                  <li class="listitem">
                    <p><b>%D.&nbsp;</b>Date</p>
                  </li>
                  <li class="listitem">
                    <p><b>%I.&nbsp;</b>Icon image name. This is
                    normally determined from the MIME type. The
                    associations are defined inside the <a class=
                    "link" href="#RCL.INSTALL.CONFIG.MIMECONF"
                    title=
                    "6.4.5.&nbsp;The mimeconf file"><code class=
                    "filename">mimeconf</code> configuration
                    file</a>. If a thumbnail for the file is found
                    at the standard Freedesktop location, this will
                    be displayed instead.</p>
                  </li>
                  <li class="listitem">
                    <p><b>%K.&nbsp;</b>Keywords (if any)</p>
                  </li>
                  <li class="listitem">
                    <p><b>%L.&nbsp;</b>Precooked Preview, Edit, and
                    possibly Snippets links</p>
                  </li>
                  <li class="listitem">
                    <p><b>%M.&nbsp;</b>MIME type</p>
                  </li>
                  <li class="listitem">
                    <p><b>%N.&nbsp;</b>result Number inside the
                    result page</p>
                  </li>
                  <li class="listitem">
                    <p><b>%P.&nbsp;</b>Parent folder Url. In the
                    case of an embedded document, this is the
                    parent folder for the top level container
                    file.</p>
                  </li>
                  <li class="listitem">
                    <p><b>%R.&nbsp;</b>Relevance percentage</p>
                  </li>
                  <li class="listitem">
                    <p><b>%S.&nbsp;</b>Size information</p>
                  </li>
                  <li class="listitem">
                    <p><b>%T.&nbsp;</b>Title or Filename if not
                    set.</p>
                  </li>
                  <li class="listitem">
                    <p><b>%t.&nbsp;</b>Title or empty.</p>
                  </li>
                  <li class="listitem">
                    <p><b>%(filename).&nbsp;</b>File name.</p>
                  </li>
                  <li class="listitem">
                    <p><b>%U.&nbsp;</b>Url</p>
                  </li>
                </ul>
              </div>
              <p>The format of the Preview, Edit, and Snippets
              links is <code class="literal">&lt;a
              href="P%N"&gt;</code>, <code class="literal">&lt;a
              href="E%N"&gt;</code> and <code class="literal">&lt;a
              href="A%N"&gt;</code> where <em class=
              "replaceable"><code>docnum</code></em> (%N) expands
              to the document number inside the result page).</p>
              <p>A link target defined as <code class=
              "literal">"F%N"</code> will open the document
              corresponding to the <code class="literal">%P</code>
              parent folder expansion, usually creating a file
              manager window on the folder where the container file
              resides. E.g.:</p>
              <pre class="programlisting">
              &lt;a href="F%N"&gt;%P&lt;/a&gt;</pre>
              <p>A link target defined as <code class=
              "literal">R%N|<em class=
              "replaceable"><code>scriptname</code></em></code>
              will run the corresponding script on the result file
              (if the document is embedded, the script will be
              started on the top-level parent). See the <a class=
              "link" href="#RCL.SEARCH.GUI.RUNSCRIPT" title=
              "3.1.4.&nbsp;Running arbitrary commands on result files (1.20 and later)">
              section about defining scripts</a>.</p>
              <p>In addition to the predefined values above, all
              strings like <code class=
              "literal">%(fieldname)</code> will be replaced by the
              value of the field named <code class=
              "literal">fieldname</code> for this document. Only
              stored fields can be accessed in this way, the value
              of indexed but not stored fields is not known at this
              point in the search process (see <a class="link"
              href="#RCL.PROGRAM.FIELDS" title=
              "5.2.&nbsp;Field data processing">field
              configuration</a>). There are currently very few
              fields stored by default, apart from the values above
              (only <code class="literal">author</code> and
              <code class="literal">filename</code>), so this
              feature will need some custom local configuration to
              be useful. An example candidate would be the
              <code class="literal">recipient</code> field which is
              generated by the message input handlers.</p>
              <p>The default value for the paragraph format string
              is:</p>
              <pre class="screen">
            "&lt;table class=\"respar\"&gt;\n"
            "&lt;tr&gt;\n"
            "&lt;td&gt;&lt;a href='%U'&gt;&lt;img src='%I' width='64'&gt;&lt;/a&gt;&lt;/td&gt;\n"
            "&lt;td&gt;%L &amp;nbsp;&lt;i&gt;%S&lt;/i&gt; &amp;nbsp;&amp;nbsp;&lt;b&gt;%T&lt;/b&gt;&lt;br&gt;\n"
            "&lt;span style='white-space:nowrap'&gt;&lt;i&gt;%M&lt;/i&gt;&amp;nbsp;%D&lt;/span&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp; &lt;i&gt;%U&lt;/i&gt;&amp;nbsp;%i&lt;br&gt;\n"
            "%A %K&lt;/td&gt;\n"
            "&lt;/tr&gt;&lt;/table&gt;\n"
            </pre>
              <p>You may, for example, try the following for a more
              web-like experience:</p>
              <pre class="screen">
            &lt;u&gt;&lt;b&gt;&lt;a href="P%N"&gt;%T&lt;/a&gt;&lt;/b&gt;&lt;/u&gt;&lt;br&gt;
            %A&lt;font color=#008000&gt;%U - %S&lt;/font&gt; - %L
            </pre>
              <p>Note that the P%N link in the above paragraph
              makes the title a preview link. Or the clean
              looking:</p>
              <pre class="screen">
            &lt;img src="%I" align="left"&gt;%L &lt;font color="#900000"&gt;%R&lt;/font&gt;
            &amp;nbsp;&amp;nbsp;&lt;b&gt;%T&amp;&lt;/b&gt;&lt;br&gt;%S&amp;nbsp;
            &lt;font color="#808080"&gt;&lt;i&gt;%U&lt;/i&gt;&lt;/font&gt;
            &lt;table bgcolor="#e0e0e0"&gt;
            &lt;tr&gt;&lt;td&gt;&lt;div&gt;%A&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
            &lt;/table&gt;%K
            </pre>
              <p>These samples, and some others are <a class=
              "ulink" href="http://www.recoll.org/custom.html"
              target="_top">on the web site, with pictures to show
              how they look.</a></p>
              <p>It is also possible to <a class="link" href=
              "#RCL.SEARCH.GUI.CUSTOM.ABSSEP">define the value of
              the snippet separator inside the abstract
              section</a>.</p>
            </div>
          </div>
        </div>
      </div>
      <div class="sect1">
        <div class="titlepage">
          <div>
            <div>
              <h2 class="title" style="clear: both"><a name=
              "RCL.SEARCH.KIO" id=
              "RCL.SEARCH.KIO"></a>3.2.&nbsp;Searching with the KDE
              KIO slave</h2>
            </div>
          </div>
        </div>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name="RCL.SEARCH.KIO.INTRO"
                id="RCL.SEARCH.KIO.INTRO"></a>3.2.1.&nbsp;What's
                this</h3>
              </div>
            </div>
          </div>
          <p>The <span class="application">Recoll</span> KIO slave
          allows performing a <span class=
          "application">Recoll</span> search by entering an
          appropriate URL in a KDE open dialog, or with an
          HTML-based interface displayed in <span class=
          "command"><strong>Konqueror</strong></span>.</p>
          <p>The HTML-based interface is similar to the Qt-based
          interface, but slightly less powerful for now. Its
          advantage is that you can perform your search while
          staying fully within the KDE framework: drag and drop
          from the result list works normally and you have your
          normal choice of applications for opening files.</p>
          <p>The alternative interface uses a directory view of
          search results. Due to limitations in the current KIO
          slave interface, it is currently not obviously useful (to
          me).</p>
          <p>The interface is described in more detail inside a
          help file which you can access by entering <code class=
          "filename">recoll:/</code> inside the <span class=
          "command"><strong>konqueror</strong></span> URL line
          (this works only if the recoll KIO slave has been
          previously installed).</p>
          <p>The instructions for building this module are located
          in the source tree. See: <code class=
          "filename">kde/kio/recoll/00README.txt</code>. Some Linux
          distributions do package the kio-recoll module, so check
          before diving into the build process, maybe it's already
          out there ready for one-click installation.</p>
        </div>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name=
                "RCL.SEARCH.KIO.SEARCHABLEDOCS" id=
                "RCL.SEARCH.KIO.SEARCHABLEDOCS"></a>3.2.2.&nbsp;Searchable
                documents</h3>
              </div>
            </div>
          </div>
          <p>As a sample application, the <span class=
          "application">Recoll</span> KIO slave could allow
          preparing a set of HTML documents (for example a manual)
          so that they become their own search interface inside
          <span class=
          "command"><strong>konqueror</strong></span>.</p>
          <p>This can be done by either explicitly inserting
          <code class="literal">&lt;a
          href="recoll://..."&gt;</code> links around some document
          areas, or automatically by adding a very small
          <span class="application">javascript</span> program to
          the documents, like the following example, which would
          initiate a search by double-clicking any term:</p>
          <pre class="programlisting">
          &lt;script language="JavaScript"&gt;
        function recollsearch() {
        var t = document.getSelection();
        window.location.href = 'recoll://search/query?qtp=a&amp;p=0&amp;q=' +
        encodeURIComponent(t);
        }
        &lt;/script&gt;
        ....
        &lt;body ondblclick="recollsearch()"&gt;

        </pre>
        </div>
      </div>
      <div class="sect1">
        <div class="titlepage">
          <div>
            <div>
              <h2 class="title" style="clear: both"><a name=
              "RCL.SEARCH.COMMANDLINE" id=
              "RCL.SEARCH.COMMANDLINE"></a>3.3.&nbsp;Searching on
              the command line</h2>
            </div>
          </div>
        </div>
        <p>There are several ways to obtain search results as a
        text stream, without a graphical interface:</p>
        <div class="itemizedlist">
          <ul class="itemizedlist" style="list-style-type: disc;">
            <li class="listitem">
              <p>By passing option <code class="option">-t</code>
              to the <span class=
              "command"><strong>recoll</strong></span> program, or
              by calling it as <span class=
              "command"><strong>recollq</strong></span> (through a
              link).</p>
            </li>
            <li class="listitem">
              <p>By using the <span class=
              "command"><strong>recollq</strong></span>
              program.</p>
            </li>
            <li class="listitem">
              <p>By writing a custom <span class=
              "application">Python</span> program, using the
              <a class="link" href="#RCL.PROGRAM.PYTHONAPI" title=
              "5.3.&nbsp;Python API">Recoll Python API</a>.</p>
            </li>
          </ul>
        </div>
        <p>The first two methods work in the same way and
        accept/need the same arguments (except for the additional
        <code class="option">-t</code> to <span class=
        "command"><strong>recoll</strong></span>). The query to be
        executed is specified as command line arguments.</p>
        <p><span class="command"><strong>recollq</strong></span> is
        not built by default. You can use the <code class=
        "filename">Makefile</code> in the <code class=
        "filename">query</code> directory to build it. This is a
        very simple program, and if you can program a little c++,
        you may find it useful to taylor its output format to your
        needs. Not that recollq is only really useful on systems
        where the Qt libraries (or even the X11 ones) are not
        available. Otherwise, just use <code class="literal">recoll
        -t</code>, which takes the exact same parameters and
        options which are described for <span class=
        "command"><strong>recollq</strong></span></p>
        <p><span class="command"><strong>recollq</strong></span>
        has a man page (not installed by default, look in the
        <code class="filename">doc/man</code> directory). The Usage
        string is as follows:</p>
        <pre class="programlisting">
        recollq: usage:
        -P: Show the date span for all the documents present in the index
        [-o|-a|-f] [-q] &lt;query string&gt;
        Runs a recoll query and displays result lines. 
        Default: will interpret the argument(s) as a xesam query string
        query may be like: 
        implicit AND, Exclusion, field spec:    t1 -t2 title:t3
        OR has priority: t1 OR t2 t3 OR t4 means (t1 OR t2) AND (t3 OR t4)
        Phrase: "t1 t2" (needs additional quoting on cmd line)
        -o Emulate the GUI simple search in ANY TERM mode
        -a Emulate the GUI simple search in ALL TERMS mode
        -f Emulate the GUI simple search in filename mode
        -q is just ignored (compatibility with the recoll GUI command line)
        Common options:
        -c &lt;configdir&gt; : specify config directory, overriding $RECOLL_CONFDIR
        -d also dump file contents
        -n [first-]&lt;cnt&gt; define the result slice. The default value for [first]
        is 0. Without the option, the default max count is 2000.
        Use n=0 for no limit
        -b : basic. Just output urls, no mime types or titles
        -Q : no result lines, just the processed query and result count
        -m : dump the whole document meta[] array for each result
        -A : output the document abstracts
        -S fld : sort by field &lt;fld&gt;
        -s stemlang : set stemming language to use (must exist in index...)
        Use -s "" to turn off stem expansion
        -D : sort descending
        -i &lt;dbdir&gt; : additional index, several can be given
        -e use url encoding (%xx) for urls
        -F &lt;field name list&gt; : output exactly these fields for each result.
        The field values are encoded in base64, output in one line and 
        separated by one space character. This is the recommended format 
        for use by other programs. Use a normal query with option -m to 
        see the field names.
      </pre>
        <p>Sample execution:</p>
        <pre class="programlisting">
        recollq 'ilur -nautique mime:text/html'
      Recoll query: ((((ilur:(wqf=11) OR ilurs) AND_NOT (nautique:(wqf=11)
      OR nautiques OR nautiqu OR nautiquement)) FILTER Ttext/html))
      4 results
      text/html       [file:///Users/uncrypted-dockes/projets/bateaux/ilur/comptes.html]      [comptes.html]  18593   bytes   
      text/html       [file:///Users/uncrypted-dockes/projets/nautique/webnautique/articles/ilur1/index.html] [Constructio...
      text/html       [file:///Users/uncrypted-dockes/projets/pagepers/index.html]    [psxtcl/writemime/recoll]...
      text/html       [file:///Users/uncrypted-dockes/projets/bateaux/ilur/factEtCie/recu-chasse-maree....
      </pre>
      </div>
      <div class="sect1">
        <div class="titlepage">
          <div>
            <div>
              <h2 class="title" style="clear: both"><a name=
              "RCL.SEARCH.SYNONYMS" id=
              "RCL.SEARCH.SYNONYMS"></a>3.4.&nbsp;Using Synonyms
              (1.22)</h2>
            </div>
          </div>
        </div>
        <p><b>Term synonyms:&nbsp;</b>there are a number of ways to
        use term synonyms for searching text:</p>
        <div class="itemizedlist">
          <ul class="itemizedlist" style="list-style-type: disc;">
            <li class="listitem">
              <p>At index creation time, they can be used to alter
              the indexed terms, either increasing or decreasing
              their number, by expanding the original terms to all
              synonyms, or by reducing all synonym terms to a
              canonical one.</p>
            </li>
            <li class="listitem">
              <p>At query time, they can be used to match texts
              containing terms which are synonyms of the ones
              specified by the user, either by expanding the query
              for all synonyms, or by reducing the user entry to
              canonical terms (the latter only works if the
              corresponding processing has been performed while
              creating the index).</p>
            </li>
          </ul>
        </div>
        <p><span class="application">Recoll</span> only uses
        synonyms at query time. A user query term which part of a
        synonym group will be optionally expanded into an
        <code class="literal">OR</code> query for all terms in the
        group.</p>
        <p>Synonym groups are defined inside ordinary text files.
        Each line in the file defines a group.</p>
        <p>Example:</p>
        <pre class="programlisting">
        hi hello "good morning"

        # not sure about "au revoir" though. Is this english ?
        bye goodbye "see you" \
        "au revoir" 
      </pre>
        <p>As usual, lines beginning with a <code class=
        "literal">#</code> are comments, empty lines are ignored,
        and lines can be continued by ending them with a
        backslash.</p>
        <p>Multi-word synonyms are supported, but be aware that
        these will generate phrase queries, which may degrade
        performance and will disable stemming expansion for the
        phrase terms.</p>
        <p>The synonyms file can be specified in the <span class=
        "guilabel">Search parameters</span> tab of the <span class=
        "guilabel">GUI configuration</span> <span class=
        "guilabel">Preferences</span> menu entry, or as an option
        for command-line searches.</p>
        <p>Once the file is defined, the use of synonyms can be
        enabled or disabled directly from the <span class=
        "guilabel">Preferences</span> menu.</p>
        <p>The synonyms are searched for matches with user terms
        after the latter are stem-expanded, but the contents of the
        synonyms file itself is not subjected to stem expansion.
        This means that a match will not be found if the form
        present in the synonyms file is not present anywhere in the
        document set.</p>
        <p>The synonyms function is probably not going to help you
        find your letters to Mr. Smith. It is best used for
        domain-specific searches. For example, it was initially
        suggested by a user performing searches among historical
        documents: the synonyms file would contains nicknames and
        aliases for each of the persons of interest.</p>
      </div>
      <div class="sect1">
        <div class="titlepage">
          <div>
            <div>
              <h2 class="title" style="clear: both"><a name=
              "RCL.SEARCH.PTRANS" id=
              "RCL.SEARCH.PTRANS"></a>3.5.&nbsp;Path
              translations</h2>
            </div>
          </div>
        </div>
        <p>In some cases, the document paths stored inside the
        index do not match the actual ones, so that document
        previews and accesses will fail. This can occur in a number
        of circumstances:</p>
        <div class="itemizedlist">
          <ul class="itemizedlist" style="list-style-type: disc;">
            <li class="listitem">
              <p>When using multiple indexes it is a relatively
              common occurrence that some will actually reside on a
              remote volume, for exemple mounted via NFS. In this
              case, the paths used to access the documents on the
              local machine are not necessarily the same than the
              ones used while indexing on the remote machine. For
              example, <code class="filename">/home/me</code> may
              have been used as a <code class=
              "literal">topdirs</code> elements while indexing, but
              the directory might be mounted as <code class=
              "filename">/net/server/home/me</code> on the local
              machine.</p>
            </li>
            <li class="listitem">
              <p>The case may also occur with removable disks. It
              is perfectly possible to configure an index to live
              with the documents on the removable disk, but it may
              happen that the disk is not mounted at the same place
              so that the documents paths from the index are
              invalid.</p>
            </li>
            <li class="listitem">
              <p>As a last exemple, one could imagine that a big
              directory has been moved, but that it is currently
              inconvenient to run the indexer.</p>
            </li>
          </ul>
        </div>
        <p><span class="application">Recoll</span> has a facility
        for rewriting access paths when extracting the data from
        the index. The translations can be defined for the main
        index and for any additional query index.</p>
        <p>The path translation facility will be useful whenever
        the documents paths seen by the indexer are not the same as
        the ones which should be used at query time.</p>
        <p>In the above NFS example, <span class=
        "application">Recoll</span> could be instructed to rewrite
        any <code class="filename">file:///home/me</code> URL from
        the index to <code class=
        "filename">file:///net/server/home/me</code>, allowing
        accesses from the client.</p>
        <p>The translations are defined in the <a class="link"
        href="#RCL.INSTALL.CONFIG.PTRANS" title=
        "6.4.7.&nbsp;The ptrans file"><code class=
        "filename">ptrans</code></a> configuration file, which can
        be edited by hand or from the GUI external indexes
        configuration dialog: <span class=
        "guimenu">Preferences</span> → <span class=
        "guimenuitem">External index dialog</span>, then click the
        <span class="guilabel">Paths translations</span> button on
        the right below the index list.</p>
        <div class="note" style=
        "margin-left: 0.5in; margin-right: 0.5in;">
          <h3 class="title">Note</h3>
          <p>Due to a current bug, the GUI must be restarted after
          changing the <code class="filename">ptrans</code> values
          (even when they were changed from the GUI).</p>
        </div>
      </div>
      <div class="sect1">
        <div class="titlepage">
          <div>
            <div>
              <h2 class="title" style="clear: both"><a name=
              "RCL.SEARCH.LANG" id=
              "RCL.SEARCH.LANG"></a>3.6.&nbsp;The query
              language</h2>
            </div>
          </div>
        </div>
        <p>The query language processor is activated in the GUI
        simple search entry when the search mode selector is set to
        <span class="guilabel">Query Language</span>. It can also
        be used with the KIO slave or the command line search. It
        broadly has the same capabilities as the complex search
        interface in the GUI.</p>
        <p>The language was based on the now defunct <a class=
        "ulink" href=
        "http://www.xesam.org/main/XesamUserSearchLanguage95"
        target="_top">Xesam</a> user search language
        specification.</p>
        <p>If the results of a query language search puzzle you and
        you doubt what has been actually searched for, you can use
        the GUI <code class="literal">Show Query</code> link at the
        top of the result list to check the exact query which was
        finally executed by Xapian.</p>
        <p>Here follows a sample request that we are going to
        explain:</p>
        <pre class="programlisting">
        author:"john doe" Beatles OR Lennon Live OR Unplugged -potatoes
      </pre>
        <p>This would search for all documents with <em class=
        "replaceable"><code>John Doe</code></em> appearing as a
        phrase in the author field (exactly what this is would
        depend on the document type, ie: the <code class=
        "literal">From:</code> header, for an email message), and
        containing either <em class=
        "replaceable"><code>beatles</code></em> or <em class=
        "replaceable"><code>lennon</code></em> and either
        <em class="replaceable"><code>live</code></em> or
        <em class="replaceable"><code>unplugged</code></em> but not
        <em class="replaceable"><code>potatoes</code></em> (in any
        part of the document).</p>
        <p>An element is composed of an optional field
        specification, and a value, separated by a colon (the field
        separator is the last colon in the element). Examples:
        <em class="replaceable"><code>Eugenie</code></em>,
        <em class="replaceable"><code>author:balzac</code></em>,
        <em class="replaceable"><code>dc:title:grandet</code></em>
        <em class="replaceable"><code>dc:title:"eugenie
        grandet"</code></em></p>
        <p>The colon, if present, means "contains". Xesam defines
        other relations, which are mostly unsupported for now
        (except in special cases, described further down).</p>
        <p>All elements in the search entry are normally combined
        with an implicit AND. It is possible to specify that
        elements be OR'ed instead, as in <em class=
        "replaceable"><code>Beatles</code></em> <code class=
        "literal">OR</code> <em class=
        "replaceable"><code>Lennon</code></em>. The <code class=
        "literal">OR</code> must be entered literally (capitals),
        and it has priority over the AND associations: <em class=
        "replaceable"><code>word1</code></em> <em class=
        "replaceable"><code>word2</code></em> <code class=
        "literal">OR</code> <em class=
        "replaceable"><code>word3</code></em> means <em class=
        "replaceable"><code>word1</code></em> AND (<em class=
        "replaceable"><code>word2</code></em> <code class=
        "literal">OR</code> <em class=
        "replaceable"><code>word3</code></em>) not (<em class=
        "replaceable"><code>word1</code></em> AND <em class=
        "replaceable"><code>word2</code></em>) <code class=
        "literal">OR</code> <em class=
        "replaceable"><code>word3</code></em>.</p>
        <p><span class="application">Recoll</span> versions 1.21
        and later, allow using parentheses to group elements, which
        will sometimes make things clearer, and may allow
        expressing combinations which would have been difficult
        otherwise.</p>
        <p>An element preceded by a <code class="literal">-</code>
        specifies a term that should <span class=
        "emphasis"><em>not</em></span> appear.</p>
        <p>As usual, words inside quotes define a phrase (the order
        of words is significant), so that <em class=
        "replaceable"><code>title:"prejudice pride"</code></em> is
        not the same as <em class=
        "replaceable"><code>title:prejudice
        title:pride</code></em>, and is unlikely to find a
        result.</p>
        <p>Words inside phrases and capitalized words are not
        stem-expanded. Wildcards may be used anywhere inside a
        term. Specifying a wild-card on the left of a term can
        produce a very slow search (or even an incorrect one if the
        expansion is truncated because of excessive size). Also see
        <a class="link" href="#RCL.SEARCH.WILDCARDS" title=
        "3.8.1.&nbsp;More about wildcards">More about
        wildcards</a>.</p>
        <p>To save you some typing, recent <span class=
        "application">Recoll</span> versions (1.20 and later)
        interpret a comma-separated list of terms as an AND list
        inside the field. Use slash characters ('/') for an OR
        list. No white space is allowed. So</p>
        <pre class="programlisting">author:john,lennon</pre>
        <p>will search for documents with <code class=
        "literal">john</code> and <code class=
        "literal">lennon</code> inside the <code class=
        "literal">author</code> field (in any order), and</p>
        <pre class="programlisting">author:john/ringo</pre>
        <p>would search for <code class="literal">john</code> or
        <code class="literal">ringo</code>.</p>
        <p>Modifiers can be set on a double-quote value, for
        example to specify a proximity search (unordered). See
        <a class="link" href="#RCL.SEARCH.LANG.MODIFIERS" title=
        "3.6.2.&nbsp;Modifiers">the modifier section</a>. No space
        must separate the final double-quote and the modifiers
        value, e.g. <em class="replaceable"><code>"two
        one"po10</code></em></p>
        <p><span class="application">Recoll</span> currently
        manages the following default fields:</p>
        <div class="itemizedlist">
          <ul class="itemizedlist" style="list-style-type: disc;">
            <li class="listitem">
              <p><code class="literal">title</code>, <code class=
              "literal">subject</code> or <code class=
              "literal">caption</code> are synonyms which specify
              data to be searched for in the document title or
              subject.</p>
            </li>
            <li class="listitem">
              <p><code class="literal">author</code> or
              <code class="literal">from</code> for searching the
              documents originators.</p>
            </li>
            <li class="listitem">
              <p><code class="literal">recipient</code> or
              <code class="literal">to</code> for searching the
              documents recipients.</p>
            </li>
            <li class="listitem">
              <p><code class="literal">keyword</code> for searching
              the document-specified keywords (few documents
              actually have any).</p>
            </li>
            <li class="listitem">
              <p><code class="literal">filename</code> for the
              document's file name. This is not necessarily set for
              all documents: internal documents contained inside a
              compound one (for example an EPUB section) do not
              inherit the container file name any more, this was
              replaced by an explicit field (see next).
              Sub-documents can still have a specific <code class=
              "literal">filename</code>, if it is implied by the
              document format, for example the attachment file name
              for an email attachment.</p>
            </li>
            <li class="listitem">
              <p><code class="literal">containerfilename</code>.
              This is set for all documents, both top-level and
              contained sub-documents, and is always the name of
              the filesystem directory entry which contains the
              data. The terms from this field can only be matched
              by an explicit field specification (as opposed to
              terms from <code class="literal">filename</code>
              which are also indexed as general document content).
              This avoids getting matches for all the sub-documents
              when searching for the container file name.</p>
            </li>
            <li class="listitem">
              <p><code class="literal">ext</code> specifies the
              file name extension (Ex: <code class=
              "literal">ext:html</code>)</p>
            </li>
          </ul>
        </div>
        <p><span class="application">Recoll</span> 1.20 and later
        have a way to specify aliases for the field names, which
        will save typing, for example by aliasing <code class=
        "literal">filename</code> to <em class=
        "replaceable"><code>fn</code></em> or <code class=
        "literal">containerfilename</code> to <em class=
        "replaceable"><code>cfn</code></em>. See the <a class=
        "link" href="#RCL.INSTALL.CONFIG.FIELDS" title=
        "6.4.3.&nbsp;The fields file">section about the
        <code class="filename">fields</code> file</a></p>
        <p>The document input handlers used while indexing have the
        possibility to create other fields with arbitrary names,
        and aliases may be defined in the configuration, so that
        the exact field search possibilities may be different for
        you if someone took care of the customisation.</p>
        <p>The field syntax also supports a few field-like, but
        special, criteria:</p>
        <div class="itemizedlist">
          <ul class="itemizedlist" style="list-style-type: disc;">
            <li class="listitem">
              <p><code class="literal">dir</code> for filtering the
              results on file location (Ex: <code class=
              "literal">dir:/home/me/somedir</code>). <code class=
              "literal">-dir</code> also works to find results not
              in the specified directory (release &gt;= 1.15.8).
              Tilde expansion will be performed as usual (except
              for a bug in versions 1.19 to 1.19.11p1). Wildcards
              will be expanded, but please <a class="link" href=
              "#RCL.SEARCH.WILDCARDS.PATH" title=
              "3.8.1.1.&nbsp;Wildcards and path filtering">have a
              look</a> at an important limitation of wildcards in
              path filters.</p>
              <p>Relative paths also make sense, for example,
              <code class="literal">dir:share/doc</code> would
              match either <code class=
              "filename">/usr/share/doc</code> or <code class=
              "filename">/usr/local/share/doc</code></p>
              <p>Several <code class="literal">dir</code> clauses
              can be specified, both positive and negative. For
              example the following makes sense:</p>
              <pre class="programlisting">
          dir:recoll dir:src -dir:utils -dir:common
          </pre>
              <p>This would select results which have both
              <code class="filename">recoll</code> and <code class=
              "filename">src</code> in the path (in any order), and
              which have not either <code class=
              "filename">utils</code> or <code class=
              "filename">common</code>.</p>
              <p>You can also use <code class="literal">OR</code>
              conjunctions with <code class="literal">dir:</code>
              clauses.</p>
              <p>A special aspect of <code class=
              "literal">dir</code> clauses is that the values in
              the index are not transcoded to UTF-8, and never
              lower-cased or unaccented, but stored as binary. This
              means that you need to enter the values in the exact
              lower or upper case, and that searches for names with
              diacritics may sometimes be impossible because of
              character set conversion issues. Non-ASCII UNIX file
              paths are an unending source of trouble and are best
              avoided.</p>
              <p>You need to use double-quotes around the path
              value if it contains space characters.</p>
            </li>
            <li class="listitem">
              <p><code class="literal">size</code> for filtering
              the results on file size. Example: <code class=
              "literal">size&lt;10000</code>. You can use
              <code class="literal">&lt;</code>, <code class=
              "literal">&gt;</code> or <code class=
              "literal">=</code> as operators. You can specify a
              range like the following: <code class=
              "literal">size&gt;100 size&lt;1000</code>. The usual
              <code class="literal">k/K, m/M, g/G, t/T</code> can
              be used as (decimal) multipliers. Ex: <code class=
              "literal">size&gt;1k</code> to search for files
              bigger than 1000 bytes.</p>
            </li>
            <li class="listitem">
              <p><code class="literal">date</code> for searching or
              filtering on dates. The syntax for the argument is
              based on the ISO8601 standard for dates and time
              intervals. Only dates are supported, no times. The
              general syntax is 2 elements separated by a
              <code class="literal">/</code> character. Each
              element can be a date or a period of time. Periods
              are specified as <code class=
              "literal">P</code><em class=
              "replaceable"><code>n</code></em><code class=
              "literal">Y</code><em class=
              "replaceable"><code>n</code></em><code class=
              "literal">M</code><em class=
              "replaceable"><code>n</code></em><code class=
              "literal">D</code>. The <em class=
              "replaceable"><code>n</code></em> numbers are the
              respective numbers of years, months or days, any of
              which may be missing. Dates are specified as
              <em class=
              "replaceable"><code>YYYY</code></em>-<em class=
              "replaceable"><code>MM</code></em>-<em class=
              "replaceable"><code>DD</code></em>. The days and
              months parts may be missing. If the <code class=
              "literal">/</code> is present but an element is
              missing, the missing element is interpreted as the
              lowest or highest date in the index. Examples:</p>
              <div class="itemizedlist">
                <ul class="itemizedlist" style=
                "list-style-type: circle;">
                  <li class="listitem">
                    <p><code class=
                    "literal">2001-03-01/2002-05-01</code> the
                    basic syntax for an interval of dates.</p>
                  </li>
                  <li class="listitem">
                    <p><code class=
                    "literal">2001-03-01/P1Y2M</code> the same
                    specified with a period.</p>
                  </li>
                  <li class="listitem">
                    <p><code class="literal">2001/</code> from the
                    beginning of 2001 to the latest date in the
                    index.</p>
                  </li>
                  <li class="listitem">
                    <p><code class="literal">2001</code> the whole
                    year of 2001</p>
                  </li>
                  <li class="listitem">
                    <p><code class="literal">P2D/</code> means 2
                    days ago up to now if there are no documents
                    with dates in the future.</p>
                  </li>
                  <li class="listitem">
                    <p><code class="literal">/2003</code> all
                    documents from 2003 or older.</p>
                  </li>
                </ul>
              </div>
              <p>Periods can also be specified with small letters
              (ie: p2y).</p>
            </li>
            <li class="listitem">
              <p><code class="literal">mime</code> or <code class=
              "literal">format</code> for specifying the MIME type.
              These clauses are processed besides the normal
              Boolean logic of the search. Multiple values will be
              OR'ed (instead of the normal AND). You can specify
              types to be excluded, with the usual <code class=
              "literal">-</code>, and use wildcards. Example:
              <em class="replaceable"><code>mime:text/*
              -mime:text/plain</code></em> Specifying an explicit
              boolean operator before a <code class=
              "literal">mime</code> specification is not supported
              and will produce strange results.</p>
            </li>
            <li class="listitem">
              <p><code class="literal">type</code> or <code class=
              "literal">rclcat</code> for specifying the category
              (as in text/media/presentation/etc.). The
              classification of MIME types in categories is defined
              in the <span class="application">Recoll</span>
              configuration (<code class=
              "filename">mimeconf</code>), and can be modified or
              extended. The default category names are those which
              permit filtering results in the main GUI screen.
              Categories are OR'ed like MIME types above, and can
              be negated with <code class="literal">-</code>.</p>
            </li>
          </ul>
        </div>
        <div class="note" style=
        "margin-left: 0.5in; margin-right: 0.5in;">
          <h3 class="title">Note</h3>
          <p><code class="literal">mime</code>, <code class=
          "literal">rclcat</code>, <code class=
          "literal">size</code> and <code class=
          "literal">date</code> criteria always affect the whole
          query (they are applied as a final filter), even if set
          with other terms inside a parenthese.</p>
        </div>
        <div class="note" style=
        "margin-left: 0.5in; margin-right: 0.5in;">
          <h3 class="title">Note</h3>
          <p><code class="literal">mime</code> (or the equivalent
          <code class="literal">rclcat</code>) is the <span class=
          "emphasis"><em>only</em></span> field with an
          <code class="literal">OR</code> default. You do need to
          use <code class="literal">OR</code> with <code class=
          "literal">ext</code> terms for example.</p>
        </div>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name="RCL.SEARCH.LANG.RANGES"
                id="RCL.SEARCH.LANG.RANGES"></a>3.6.1.&nbsp;Range
                clauses</h3>
              </div>
            </div>
          </div>
          <p><span class="application">Recoll</span> 1.24 and later
          support range clauses on fields which have been
          configured to support it. No default field uses them
          currently, so this paragraph is only interesting if you
          modified the fields configuration and possibly use a
          custom input handler.</p>
          <p>A range clause looks like one of the following:</p>
          <pre class="programlisting"><em class=
          "replaceable"><code>myfield</code></em>:<em class=
          "replaceable"><code>small</code></em>..<em class=
          "replaceable"><code>big</code></em>
<em class="replaceable"><code>myfield</code></em>:<em class=
"replaceable"><code>small</code></em>..
<em class="replaceable"><code>myfield</code></em>:..<em class=
"replaceable"><code>big</code></em>
        </pre>
          <p>The nature of the clause is indicated by the two dots
          <code class="literal">..</code>, and the effect is to
          filter the results for which the <em class=
          "replaceable"><code>myfield</code></em> value is in the
          possibly open-ended interval.</p>
          <p>See the section about the <a class="link" href=
          "#RCL.INSTALL.CONFIG.FIELDS" title=
          "6.4.3.&nbsp;The fields file"><code class=
          "filename">fields</code> configuration file</a> for the
          details of configuring a field for range searches (list
          them in the [values] section).</p>
        </div>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name=
                "RCL.SEARCH.LANG.MODIFIERS" id=
                "RCL.SEARCH.LANG.MODIFIERS"></a>3.6.2.&nbsp;Modifiers</h3>
              </div>
            </div>
          </div>
          <p>Some characters are recognized as search modifiers
          when found immediately after the closing double quote of
          a phrase, as in <code class="literal">"some
          term"modifierchars</code>. The actual "phrase" can be a
          single term of course. Supported modifiers:</p>
          <div class="itemizedlist">
            <ul class="itemizedlist" style=
            "list-style-type: disc;">
              <li class="listitem">
                <p><code class="literal">l</code> can be used to
                turn off stemming (mostly makes sense with
                <code class="literal">p</code> because stemming is
                off by default for phrases).</p>
              </li>
              <li class="listitem">
                <p><code class="literal">s</code> can be used to
                turn off synonym expansion, if a synonyms file is
                in place (only for <span class=
                "application">Recoll</span> 1.22 and later).</p>
              </li>
              <li class="listitem">
                <p><code class="literal">o</code> can be used to
                specify a "slack" for phrase and proximity
                searches: the number of additional terms that may
                be found between the specified ones. If
                <code class="literal">o</code> is followed by an
                integer number, this is the slack, else the default
                is 10.</p>
              </li>
              <li class="listitem">
                <p><code class="literal">p</code> can be used to
                turn the default phrase search into a proximity one
                (unordered). Example: <code class="literal">"order
                any in"p</code></p>
              </li>
              <li class="listitem">
                <p><code class="literal">C</code> will turn on case
                sensitivity (if the index supports it).</p>
              </li>
              <li class="listitem">
                <p><code class="literal">D</code> will turn on
                diacritics sensitivity (if the index supports
                it).</p>
              </li>
              <li class="listitem">
                <p>A weight can be specified for a query element by
                specifying a decimal value at the start of the
                modifiers. Example: <code class=
                "literal">"Important"2.5</code>.</p>
              </li>
            </ul>
          </div>
        </div>
      </div>
      <div class="sect1">
        <div class="titlepage">
          <div>
            <div>
              <h2 class="title" style="clear: both"><a name=
              "RCL.SEARCH.CASEDIAC" id=
              "RCL.SEARCH.CASEDIAC"></a>3.7.&nbsp;Search case and
              diacritics sensitivity</h2>
            </div>
          </div>
        </div>
        <p>For <span class="application">Recoll</span> versions
        1.18 and later, and <span class="emphasis"><em>when working
        with a raw index</em></span> (not the default), searches
        can be sensitive to character case and diacritics. How this
        happens is controlled by configuration variables and what
        search data is entered.</p>
        <p>The general default is that searches entered without
        upper-case or accented characters are insensitive to case
        and diacritics. An entry of <code class=
        "literal">resume</code> will match any of <code class=
        "literal">Resume</code>, <code class=
        "literal">RESUME</code>, <code class=
        "literal">résumé</code>, <code class=
        "literal">Résumé</code> etc.</p>
        <p>Two configuration variables can automate switching on
        sensitivity (they were documented but actually did nothing
        until <span class="application">Recoll</span> 1.22):</p>
        <div class="variablelist">
          <dl class="variablelist">
            <dt><span class="term">autodiacsens</span></dt>
            <dd>
              <p>If this is set, search sensitivity to diacritics
              will be turned on as soon as an accented character
              exists in a search term. When the variable is set to
              true, <code class="literal">resume</code> will start
              a diacritics-unsensitive search, but <code class=
              "literal">résumé</code> will be matched exactly. The
              default value is <span class=
              "emphasis"><em>false</em></span>.</p>
            </dd>
            <dt><span class="term">autocasesens</span></dt>
            <dd>
              <p>If this is set, search sensitivity to character
              case will be turned on as soon as an upper-case
              character exists in a search term <span class=
              "emphasis"><em>except for the first one</em></span>.
              When the variable is set to true, <code class=
              "literal">us</code> or <code class=
              "literal">Us</code> will start a
              diacritics-unsensitive search, but <code class=
              "literal">US</code> will be matched exactly. The
              default value is <span class=
              "emphasis"><em>true</em></span> (contrary to
              <code class="literal">autodiacsens</code>).</p>
            </dd>
          </dl>
        </div>
        <p>As in the past, capitalizing the first letter of a word
        will turn off its stem expansion and have no effect on
        case-sensitivity.</p>
        <p>You can also explicitely activate case and diacritics
        sensitivity by using modifiers with the query language.
        <code class="literal">C</code> will make the term
        case-sensitive, and <code class="literal">D</code> will
        make it diacritics-sensitive. Examples:</p>
        <pre class="programlisting">
        "us"C
      </pre>
        <p>will search for the term <code class="literal">us</code>
        exactly (<code class="literal">Us</code> will not be a
        match).</p>
        <pre class="programlisting">
        "resume"D
      </pre>
        <p>will search for the term <code class=
        "literal">resume</code> exactly (<code class=
        "literal">résumé</code> will not be a match).</p>
        <p>When either case or diacritics sensitivity is activated,
        stem expansion is turned off. Having both does not make
        much sense.</p>
      </div>
      <div class="sect1">
        <div class="titlepage">
          <div>
            <div>
              <h2 class="title" style="clear: both"><a name=
              "RCL.SEARCH.ANCHORWILD" id=
              "RCL.SEARCH.ANCHORWILD"></a>3.8.&nbsp;Anchored
              searches and wildcards</h2>
            </div>
          </div>
        </div>
        <p>Some special characters are interpreted by <span class=
        "application">Recoll</span> in search strings to expand or
        specialize the search. Wildcards expand a root term in
        controlled ways. Anchor characters can restrict a search to
        succeed only if the match is found at or near the beginning
        of the document or one of its fields.</p>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name="RCL.SEARCH.WILDCARDS"
                id="RCL.SEARCH.WILDCARDS"></a>3.8.1.&nbsp;More
                about wildcards</h3>
              </div>
            </div>
          </div>
          <p>All words entered in <span class=
          "application">Recoll</span> search fields will be
          processed for wildcard expansion before the request is
          finally executed.</p>
          <p>The wildcard characters are:</p>
          <div class="itemizedlist">
            <ul class="itemizedlist" style=
            "list-style-type: disc;">
              <li class="listitem">
                <p><code class="literal">*</code> which matches 0
                or more characters.</p>
              </li>
              <li class="listitem">
                <p><code class="literal">?</code> which matches a
                single character.</p>
              </li>
              <li class="listitem">
                <p><code class="literal">[]</code> which allow
                defining sets of characters to be matched (ex:
                <code class="literal">[</code><strong class=
                "userinput"><code>abc</code></strong><code class=
                "literal">]</code> matches a single character which
                may be 'a' or 'b' or 'c', <code class=
                "literal">[</code><strong class=
                "userinput"><code>0-9</code></strong><code class=
                "literal">]</code> matches any number.</p>
              </li>
            </ul>
          </div>
          <p>You should be aware of a few things when using
          wildcards.</p>
          <div class="itemizedlist">
            <ul class="itemizedlist" style=
            "list-style-type: disc;">
              <li class="listitem">
                <p>Using a wildcard character at the beginning of a
                word can make for a slow search because
                <span class="application">Recoll</span> will have
                to scan the whole index term list to find the
                matches. However, this is much less a problem for
                field searches, and queries like <em class=
                "replaceable"><code>author:*@domain.com</code></em>
                can sometimes be very useful.</p>
              </li>
              <li class="listitem">
                <p>For <span class="application">Recoll</span>
                version 18 only, when working with a raw index
                (preserving character case and diacritics), the
                literal part of a wildcard expression will be
                matched exactly for case and diacritics. This is
                not true any more for versions 19 and later.</p>
              </li>
              <li class="listitem">
                <p>Using a <code class="literal">*</code> at the
                end of a word can produce more matches than you
                would think, and strange search results. You can
                use the <a class="link" href=
                "#RCL.SEARCH.GUI.TERMEXPLORER" title=
                "3.1.9.&nbsp;The term explorer tool">term
                explorer</a> tool to check what completions exist
                for a given term. You can also see exactly what
                search was performed by clicking on the link at the
                top of the result list. In general, for natural
                language terms, stem expansion will produce better
                results than an ending <code class=
                "literal">*</code> (stem expansion is turned off
                when any wildcard character appears in the
                term).</p>
              </li>
            </ul>
          </div>
          <div class="sect3">
            <div class="titlepage">
              <div>
                <div>
                  <h4 class="title"><a name=
                  "RCL.SEARCH.WILDCARDS.PATH" id=
                  "RCL.SEARCH.WILDCARDS.PATH"></a>3.8.1.1.&nbsp;Wildcards
                  and path filtering</h4>
                </div>
              </div>
            </div>
            <p>Due to the way that <span class=
            "application">Recoll</span> processes wildcards inside
            <code class="literal">dir</code> path filtering
            clauses, they will have a multiplicative effect on the
            query size. A clause containg wildcards in several
            paths elements, like, for example, <code class=
            "literal">dir:</code><em class=
            "replaceable"><code>/home/me/*/*/docdir</code></em>,
            will almost certainly fail if your indexed tree is of
            any realistic size.</p>
            <p>Depending on the case, you may be able to work
            around the issue by specifying the paths elements more
            narrowly, with a constant prefix, or by using 2
            separate <code class="literal">dir:</code> clauses
            instead of multiple wildcards, as in <code class=
            "literal">dir:</code><em class=
            "replaceable"><code>/home/me</code></em> <code class=
            "literal">dir:</code><em class=
            "replaceable"><code>docdir</code></em>. The latter
            query is not equivalent to the initial one because it
            does not specify a number of directory levels, but
            that's the best we can do (and it may be actually more
            useful in some cases).</p>
          </div>
        </div>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name="RCL.SEARCH.ANCHOR" id=
                "RCL.SEARCH.ANCHOR"></a>3.8.2.&nbsp;Anchored
                searches</h3>
              </div>
            </div>
          </div>
          <p>Two characters are used to specify that a search hit
          should occur at the beginning or at the end of the text.
          <code class="literal">^</code> at the beginning of a term
          or phrase constrains the search to happen at the start,
          <code class="literal">$</code> at the end force it to
          happen at the end.</p>
          <p>As this function is implemented as a phrase search it
          is possible to specify a maximum distance at which the
          hit should occur, either through the controls of the
          advanced search panel, or using the query language, for
          example, as in:</p>
          <pre class="programlisting">"^someterm"o10</pre>
          <p>which would force <code class=
          "literal">someterm</code> to be found within 10 terms of
          the start of the text. This can be combined with a field
          search as in <code class=
          "literal">somefield:"^someterm"o10</code> or <code class=
          "literal">somefield:someterm$</code>.</p>
          <p>This feature can also be used with an actual phrase
          search, but in this case, the distance applies to the
          whole phrase and anchor, so that, for example,
          <code class="literal">bla bla my unexpected term</code>
          at the beginning of the text would be a match for
          <code class="literal">"^my term"o5</code>.</p>
          <p>Anchored searches can be very useful for searches
          inside somewhat structured documents like scientific
          articles, in case explicit metadata has not been supplied
          (a most frequent case), for example for looking for
          matches inside the abstract or the list of authors (which
          occur at the top of the document).</p>
        </div>
      </div>
      <div class="sect1">
        <div class="titlepage">
          <div>
            <div>
              <h2 class="title" style="clear: both"><a name=
              "RCL.SEARCH.DESKTOP" id=
              "RCL.SEARCH.DESKTOP"></a>3.9.&nbsp;Desktop
              integration</h2>
            </div>
          </div>
        </div>
        <p>Being independant of the desktop type has its drawbacks:
        <span class="application">Recoll</span> desktop integration
        is minimal. However there are a few tools available:</p>
        <div class="itemizedlist">
          <ul class="itemizedlist" style="list-style-type: disc;">
            <li class="listitem">
              <p>The <span class="application">KDE</span> KIO Slave
              was described in a <a class="link" href=
              "#RCL.SEARCH.KIO" title=
              "3.2.&nbsp;Searching with the KDE KIO slave">previous
              section</a>.</p>
            </li>
            <li class="listitem">
              <p>If you use a recent version of Ubuntu Linux, you
              may find the <a class="ulink" href=
              "https://www.lesbonscomptes.com/recoll/faqsandhowtos/UnityLens"
              target="_top">Ubuntu Unity Lens</a> module
              useful.</p>
            </li>
            <li class="listitem">
              <p>There is also an independantly developed <a class=
              "ulink" href=
              "http://kde-apps.org/content/show.php/recollrunner?content=128203"
              target="_top">Krunner plugin</a>.</p>
            </li>
          </ul>
        </div>
        <p>Here follow a few other things that may help.</p>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name="RCL.SEARCH.SHORTCUT" id=
                "RCL.SEARCH.SHORTCUT"></a>3.9.1.&nbsp;Hotkeying
                recoll</h3>
              </div>
            </div>
          </div>
          <p>It is surprisingly convenient to be able to show or
          hide the <span class="application">Recoll</span> GUI with
          a single keystroke. Recoll comes with a small Python
          script, based on the <span class=
          "application">libwnck</span> window manager interface
          library, which will allow you to do just this. The
          detailed instructions are on <a class="ulink" href=
          "https://www.lesbonscomptes.com/recoll/faqsandhowtos/HotRecoll"
          target="_top">this wiki page</a>.</p>
        </div>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name="RCL.KICKER-APPLET" id=
                "RCL.KICKER-APPLET"></a>3.9.2.&nbsp;The KDE Kicker
                Recoll applet</h3>
              </div>
            </div>
          </div>
          <p>This is probably obsolete now. Anyway:</p>
          <p>The <span class="application">Recoll</span> source
          tree contains the source code to the <span class=
          "application">recoll_applet</span>, a small application
          derived from the <span class=
          "application">find_applet</span>. This can be used to add
          a small <span class="application">Recoll</span> launcher
          to the KDE panel.</p>
          <p>The applet is not automatically built with the main
          <span class="application">Recoll</span> programs, nor is
          it included with the main source distribution (because
          the KDE build boilerplate makes it relatively big). You
          can download its source from the recoll.org download
          page. Use the omnipotent <strong class=
          "userinput"><code>configure;make;make
          install</code></strong> incantation to build and
          install.</p>
          <p>You can then add the applet to the panel by
          right-clicking the panel and choosing the <span class=
          "guilabel">Add applet</span> entry.</p>
          <p>The <span class="application">recoll_applet</span> has
          a small text window where you can type a <span class=
          "application">Recoll</span> query (in query language
          form), and an icon which can be used to restrict the
          search to certain types of files. It is quite primitive,
          and launches a new recoll GUI instance every time (even
          if it is already running). You may find it useful
          anyway.</p>
        </div>
      </div>
    </div>
    <div class="chapter">
      <div class="titlepage">
        <div>
          <div>
            <h1 class="title"><a name="RCL.REMOVABLE" id=
            "RCL.REMOVABLE"></a>Chapter&nbsp;4.&nbsp;Removable
            volumes</h1>
          </div>
        </div>
      </div>
      <p><span class="application">Recoll</span> used to have no
      support for indexing removable volumes (portable disks, USB
      keys, etc.). Recent versions have improved the situation and
      support indexing removable volumes in two different ways:</p>
      <div class="itemizedlist">
        <ul class="itemizedlist" style="list-style-type: disc;">
          <li class="listitem">
            <p>By storing a volume index on the volume itself
            (<span class="application">Recoll</span> 1.24).</p>
          </li>
          <li class="listitem">
            <p>By indexing the volume in the main, fixed, index,
            and ensuring that the volume data is not purged if the
            indexing runs while the volume is mounted.
            (<span class="application">Recoll</span> 1.25.2).</p>
          </li>
        </ul>
      </div>
      <div class="sect1">
        <div class="titlepage">
          <div>
            <div>
              <h2 class="title" style="clear: both"><a name=
              "RCL.REMOVABLE.MAIN" id=
              "RCL.REMOVABLE.MAIN"></a>4.1.&nbsp;Indexing removable
              volumes in the main index</h2>
            </div>
          </div>
        </div>
        <p>As of version 1.25.2, <span class=
        "application">Recoll</span> has a simple way to ensure that
        the index data for an absent volume will not be purged: the
        volume mount point must be a member of the <code class=
        "literal">topdirs</code> list, and the mount directory must
        be empty (when the volume is not mounted). If <span class=
        "command"><strong>recollindex</strong></span> finds that
        one of the <code class="literal">topdirs</code> is empty
        when starting up, any existing data for the tree will be
        preserved by the indexing pass (no purge for this
        area).</p>
      </div>
      <div class="sect1">
        <div class="titlepage">
          <div>
            <div>
              <h2 class="title" style="clear: both"><a name=
              "RCL.REMOVABLE.SELF" id=
              "RCL.REMOVABLE.SELF"></a>4.2.&nbsp;Self contained
              volumes</h2>
            </div>
          </div>
        </div>
        <p>As of <span class="application">Recoll</span> 1.24, it
        has become easy to build self-contained datasets including
        a <span class="application">Recoll</span> configuration
        directory and index together with the indexed documents,
        and to move such a dataset around (for example copying it
        to an USB drive), without having to adjust the
        configuration for querying the index.</p>
        <div class="note" style=
        "margin-left: 0.5in; margin-right: 0.5in;">
          <h3 class="title">Note</h3>
          <p>This is a query-time feature only. The index must only
          be updated in its original location. If an update is
          necessary in a different location, the index must be
          reset.</p>
        </div>
        <p>To make a long story short, here follows a script to
        create a <span class="application">Recoll</span>
        configuration and index under a given directory (given as
        single parameter). The resulting data set (files + recoll
        directory) can later to be moved to a CDROM or thumb drive.
        Longer explanations come after the script.</p>
        <pre class="programlisting">#!/bin/sh

fatal()
{
    echo $*;exit 1
}
usage()
{
    fatal "Usage: init-recoll-volume.sh &lt;top-directory&gt;"
}

test $# = 1 || usage
topdir=$1
test -d "$topdir" || fatal $topdir should be a directory

confdir="$topdir/recoll-config"
test ! -d "$confdir" || fatal $confdir should not exist

mkdir "$confdir"
cd "$topdir"
topdir=`pwd`
cd "$confdir"
confdir=`pwd`

(echo topdirs = '"'$topdir'"'; \
 echo orgidxconfdir = $topdir/recoll-config) &gt; "$confdir/recoll.conf"

recollindex -c "$confdir"
</pre>
        <p>The examples below will assume that you have a dataset
        under <code class="filename">/home/me/mydata/</code>, with
        the index configuration and data stored inside <code class=
        "filename">/home/me/mydata/recoll-confdir</code>.</p>
        <p>In order to be able to run queries after the dataset has
        been moved, you must ensure the following:</p>
        <div class="itemizedlist">
          <ul class="itemizedlist" style="list-style-type: disc;">
            <li class="listitem">
              <p>The main configuration file must define the
              <a class="link" href=
              "#RCL.INSTALL.CONFIG.RECOLLCONF.ORGIDXCONFDIR">orgidxconfdir</a>
              variable to be the original location of the
              configuration directory (<code class=
              "filename">orgidxconfdir=/home/me/mydata/recoll-confdir</code>
              must be set inside <code class=
              "filename">/home/me/mydata/recoll-confdir/recoll.conf</code>
              in the example above).</p>
            </li>
            <li class="listitem">
              <p>The configuration directory must exist with the
              documents, somewhere under the directory which will
              be moved. E.g. if you are moving <code class=
              "filename">/home/me/mydata</code> around, the
              configuration directory must exist somewhere below
              this point, for example <code class=
              "filename">/home/me/mydata/recoll-confdir</code>, or
              <code class=
              "filename">/home/me/mydata/sub/recoll-confdir</code>.</p>
            </li>
            <li class="listitem">
              <p>You should keep the default locations for the
              index elements (they are relative to the
              configuration directory by default). Only the paths
              referring to the documents themselves (e.g.
              <code class="literal">topdirs</code> values) should
              be absolute (in general, they are only used when
              indexing anyway).</p>
            </li>
          </ul>
        </div>
        <p>Only the first point needs an explicit user action, the
        <span class="application">Recoll</span> defaults are
        compatible with the second one, and the third is
        natural.</p>
        <p>If, after the move, the configuration directory needs to
        be copied out of the dataset (for example because the thumb
        drive is too slow), you can set the <a class="link" href=
        "#RCL.INSTALL.CONFIG.RECOLLCONF.CURIDXCONFDIR">curidxconfdir</a>,
        variable inside the copied configuration to define the
        location of the moved one. For example if <code class=
        "filename">/home/me/mydata</code> is now mounted onto
        <code class="filename">/media/me/somelabel</code>, but the
        configuration directory and index has been copied to
        <code class="filename">/tmp/tempconfig</code>, you would
        set <code class="literal">curidxconfdir</code> to
        <code class=
        "filename">/media/me/somelabel/recoll-confdir</code> inside
        <code class="filename">/tmp/tempconfig/recoll.conf</code>.
        <code class="literal">orgidxconfdir</code> would still be
        <code class=
        "filename">/home/me/mydata/recoll-confdir</code> in the
        original and the copy.</p>
        <p>If you are regularly copying the configuration out of
        the dataset, it will be useful to write a script to
        automate the procedure. This can't really be done inside
        <span class="application">Recoll</span> because there are
        probably many possible variants. One example would be to
        copy the configuration to make it writable, but keep the
        index data on the medium because it is too big - in this
        case, the script would also need to set <code class=
        "literal">dbdir</code> in the copied configuration.</p>
        <p>The same set of modifications (<span class=
        "application">Recoll</span> 1.24) has also made it possible
        to run queries from a readonly configuration directory
        (with slightly reduced function of course, such as not
        recording the query history).</p>
      </div>
    </div>
    <div class="chapter">
      <div class="titlepage">
        <div>
          <div>
            <h1 class="title"><a name="RCL.PROGRAM" id=
            "RCL.PROGRAM"></a>Chapter&nbsp;5.&nbsp;Programming
            interface</h1>
          </div>
        </div>
      </div>
      <p><span class="application">Recoll</span> has an Application
      Programming Interface, usable both for indexing and
      searching, currently accessible from the <span class=
      "application">Python</span> language.</p>
      <p>Another less radical way to extend the application is to
      write input handlers for new types of documents.</p>
      <p>The processing of metadata attributes for documents
      (<code class="literal">fields</code>) is highly
      configurable.</p>
      <div class="sect1">
        <div class="titlepage">
          <div>
            <div>
              <h2 class="title" style="clear: both"><a name=
              "RCL.PROGRAM.FILTERS" id=
              "RCL.PROGRAM.FILTERS"></a>5.1.&nbsp;Writing a
              document input handler</h2>
            </div>
          </div>
        </div>
        <div class="note" style=
        "margin-left: 0.5in; margin-right: 0.5in;">
          <h3 class="title">Terminology</h3>
          <p>The small programs or pieces of code which handle the
          processing of the different document types for
          <span class="application">Recoll</span> used to be called
          <code class="literal">filters</code>, which is still
          reflected in the name of the directory which holds them
          and many configuration variables. They were named this
          way because one of their primary functions is to filter
          out the formatting directives and keep the text content.
          However these modules may have other behaviours, and the
          term <code class="literal">input handler</code> is now
          progressively substituted in the documentation.
          <code class="literal">filter</code> is still used in many
          places though.</p>
        </div>
        <p><span class="application">Recoll</span> input handlers
        cooperate to translate from the multitude of input document
        formats, simple ones as <span class=
        "application">opendocument</span>, <span class=
        "application">acrobat</span>), or compound ones such as
        <span class="application">Zip</span> or <span class=
        "application">Email</span>, into the final <span class=
        "application">Recoll</span> indexing input format, which is
        plain text. Most input handlers are executable programs or
        scripts. A few handlers are coded in C++ and live inside
        <span class="command"><strong>recollindex</strong></span>.
        This latter kind will not be described here.</p>
        <p>There are currently (since version 1.13) two kinds of
        external executable input handlers:</p>
        <div class="itemizedlist">
          <ul class="itemizedlist" style="list-style-type: disc;">
            <li class="listitem">
              <p>Simple <code class="literal">exec</code> handlers
              run once and exit. They can be bare programs like
              <span class=
              "command"><strong>antiword</strong></span>, or
              scripts using other programs. They are very simple to
              write, because they just need to print the converted
              document to the standard output. Their output can be
              plain text or HTML. HTML is usually preferred because
              it can store metadata fields and it allows preserving
              some of the formatting for the GUI preview.</p>
            </li>
            <li class="listitem">
              <p>Multiple <code class="literal">execm</code>
              handlers can process multiple files (sparing the
              process startup time which can be very significant),
              or multiple documents per file (e.g.: for
              <span class="application">zip</span> or <span class=
              "application">chm</span> files). They communicate
              with the indexer through a simple protocol, but are
              nevertheless a bit more complicated than the older
              kind. Most of new handlers are written in
              <span class="application">Python</span>, using a
              common module to handle the protocol. There is an
              exception, <span class=
              "command"><strong>rclimg</strong></span> which is
              written in Perl. The subdocuments output by these
              handlers can be directly indexable (text or HTML), or
              they can be other simple or compound documents that
              will need to be processed by another handler.</p>
            </li>
          </ul>
        </div>
        <p>In both cases, handlers deal with regular file system
        files, and can process either a single document, or a
        linear list of documents in each file. <span class=
        "application">Recoll</span> is responsible for performing
        up to date checks, deal with more complex embedding and
        other upper level issues.</p>
        <p>A simple handler returning a document in <code class=
        "literal">text/plain</code> format, can transfer no
        metadata to the indexer. Generic metadata, like document
        size or modification date, will be gathered and stored by
        the indexer.</p>
        <p>Handlers that produce <code class=
        "literal">text/html</code> format can return an arbitrary
        amount of metadata inside HTML <code class=
        "literal">meta</code> tags. These will be processed
        according to the directives found in the <a class="link"
        href="#RCL.PROGRAM.FIELDS" title=
        "5.2.&nbsp;Field data processing"><code class=
        "filename">fields</code> configuration file</a>.</p>
        <p>The handlers that can handle multiple documents per file
        return a single piece of data to identify each document
        inside the file. This piece of data, called an <code class=
        "literal">ipath element</code> will be sent back by
        <span class="application">Recoll</span> to extract the
        document at query time, for previewing, or for creating a
        temporary file to be opened by a viewer.</p>
        <p>The following section describes the simple handlers, and
        the next one gives a few explanations about the
        <code class="literal">execm</code> ones. You could
        conceivably write a simple handler with only the elements
        in the manual. This will not be the case for the other
        ones, for which you will have to look at the code.</p>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name=
                "RCL.PROGRAM.FILTERS.SIMPLE" id=
                "RCL.PROGRAM.FILTERS.SIMPLE"></a>5.1.1.&nbsp;Simple
                input handlers</h3>
              </div>
            </div>
          </div>
          <p><span class="application">Recoll</span> simple
          handlers are usually shell-scripts, but this is in no way
          necessary. Extracting the text from the native format is
          the difficult part. Outputting the format expected by
          <span class="application">Recoll</span> is trivial.
          Happily enough, most document formats have translators or
          text extractors which can be called from the handler. In
          some cases the output of the translating program is
          completely appropriate, and no intermediate shell-script
          is needed.</p>
          <p>Input handlers are called with a single argument which
          is the source file name. They should output the result to
          stdout.</p>
          <p>When writing a handler, you should decide if it will
          output plain text or HTML. Plain text is simpler, but you
          will not be able to add metadata or vary the output
          character encoding (this will be defined in a
          configuration file). Additionally, some formatting may be
          easier to preserve when previewing HTML. Actually the
          deciding factor is metadata: <span class=
          "application">Recoll</span> has a way to <a class="link"
          href="#RCL.PROGRAM.FILTERS.HTML" title=
          "5.1.4.&nbsp;Input handler output">extract metadata from
          the HTML header and use it for field searches.</a>.</p>
          <p>The <code class=
          "envar">RECOLL_FILTER_FORPREVIEW</code> environment
          variable (values <code class="literal">yes</code>,
          <code class="literal">no</code>) tells the handler if the
          operation is for indexing or previewing. Some handlers
          use this to output a slightly different format, for
          example stripping uninteresting repeated keywords (ie:
          <code class="literal">Subject:</code> for email) when
          indexing. This is not essential.</p>
          <p>You should look at one of the simple handlers, for
          example <span class=
          "command"><strong>rclps</strong></span> for a starting
          point.</p>
          <p>Don't forget to make your handler executable before
          testing !</p>
        </div>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name=
                "RCL.PROGRAM.FILTERS.MULTIPLE" id=
                "RCL.PROGRAM.FILTERS.MULTIPLE"></a>5.1.2.&nbsp;"Multiple"
                handlers</h3>
              </div>
            </div>
          </div>
          <p>If you can program and want to write an <code class=
          "literal">execm</code> handler, it should not be too
          difficult to make sense of one of the existing modules.
          There is a sample one with many comments, not actually
          used by <span class="application">Recoll</span>, which
          would index a text file as one document per line. Look
          for <code class="filename">rcltxtlines.py</code> in the
          <code class="filename">src/filters</code> directory in
          the <span class="application">Recoll</span> <a class=
          "ulink" href="https://bitbucket.org/medoc/recoll/src"
          target="_top">BitBucket repository</a> (the sample not in
          the distributed release at the moment).</p>
          <p>You can also have a look at the slightly more complex
          <span class="command"><strong>rclzip</strong></span>
          which uses Zip file paths as identifiers (<code class=
          "literal">ipath</code>).</p>
          <p><code class="literal">execm</code> handlers sometimes
          need to make a choice for the nature of the <code class=
          "literal">ipath</code> elements that they use in
          communication with the indexer. Here are a few
          guidelines:</p>
          <div class="itemizedlist">
            <ul class="itemizedlist" style=
            "list-style-type: disc;">
              <li class="listitem">
                <p>Use ASCII or UTF-8 (if the identifier is an
                integer print it, for example, like printf %d would
                do).</p>
              </li>
              <li class="listitem">
                <p>If at all possible, the data should make some
                kind of sense when printed to a log file to help
                with debugging.</p>
              </li>
              <li class="listitem">
                <p><span class="application">Recoll</span> uses a
                colon (<code class="literal">:</code>) as a
                separator to store a complex path internally (for
                deeper embedding). Colons inside the <code class=
                "literal">ipath</code> elements output by a handler
                will be escaped, but would be a bad choice as a
                handler-specific separator (mostly, again, for
                debugging issues).</p>
              </li>
            </ul>
          </div>
          <p>In any case, the main goal is that it should be easy
          for the handler to extract the target document, given the
          file name and the <code class="literal">ipath</code>
          element.</p>
          <p><code class="literal">execm</code> handlers will also
          produce a document with a null <code class=
          "literal">ipath</code> element. Depending on the type of
          document, this may have some associated data (e.g. the
          body of an email message), or none (typical for an
          archive file). If it is empty, this document will be
          useful anyway for some operations, as the parent of the
          actual data documents.</p>
        </div>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name=
                "RCL.PROGRAM.FILTERS.ASSOCIATION" id=
                "RCL.PROGRAM.FILTERS.ASSOCIATION"></a>5.1.3.&nbsp;Telling
                <span class="application">Recoll</span> about the
                handler</h3>
              </div>
            </div>
          </div>
          <p>There are two elements that link a file to the handler
          which should process it: the association of file to MIME
          type and the association of a MIME type with a
          handler.</p>
          <p>The association of files to MIME types is mostly based
          on name suffixes. The types are defined inside the
          <a class="link" href="#RCL.INSTALL.CONFIG.MIMEMAP" title=
          "6.4.4.&nbsp;The mimemap file"><code class=
          "filename">mimemap</code> file</a>. Example:</p>
          <pre class="programlisting">

            .doc = application/msword
          </pre>
          <p>If no suffix association is found for the file name,
          <span class="application">Recoll</span> will try to
          execute a system command (typically <span class=
          "command"><strong>file -i</strong></span> or <span class=
          "command"><strong>xdg-mime</strong></span>) to determine
          a MIME type.</p>
          <p>The second element is the association of MIME types to
          handlers in the <a class="link" href=
          "#RCL.INSTALL.CONFIG.MIMECONF" title=
          "6.4.5.&nbsp;The mimeconf file"><code class=
          "filename">mimeconf</code> file</a>. A sample will
          probably be better than a long explanation:</p>
          <pre class="programlisting">

          [index]
          application/msword = exec antiword -t -i 1 -m UTF-8;\
          mimetype = text/plain ; charset=utf-8

          application/ogg = exec rclogg

          text/rtf = exec unrtf --nopict --html; charset=iso-8859-1; mimetype=text/html

          application/x-chm = execm rclchm
        </pre>
          <p>The fragment specifies that:</p>
          <div class="itemizedlist">
            <ul class="itemizedlist" style=
            "list-style-type: disc;">
              <li class="listitem">
                <p><code class="literal">application/msword</code>
                files are processed by executing the <span class=
                "command"><strong>antiword</strong></span> program,
                which outputs <code class=
                "literal">text/plain</code> encoded in <code class=
                "literal">utf-8</code>.</p>
              </li>
              <li class="listitem">
                <p><code class="literal">application/ogg</code>
                files are processed by the <span class=
                "command"><strong>rclogg</strong></span> script,
                with default output type (<code class=
                "literal">text/html</code>, with encoding specified
                in the header, or <code class=
                "literal">utf-8</code> by default).</p>
              </li>
              <li class="listitem">
                <p><code class="literal">text/rtf</code> is
                processed by <span class=
                "command"><strong>unrtf</strong></span>, which
                outputs <code class="literal">text/html</code>. The
                <code class="literal">iso-8859-1</code> encoding is
                specified because it is not the <code class=
                "literal">utf-8</code> default, and not output by
                <span class="command"><strong>unrtf</strong></span>
                in the HTML header section.</p>
              </li>
              <li class="listitem">
                <p><code class="literal">application/x-chm</code>
                is processed by a persistant handler. This is
                determined by the <code class=
                "literal">execm</code> keyword.</p>
              </li>
            </ul>
          </div>
        </div>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name=
                "RCL.PROGRAM.FILTERS.HTML" id=
                "RCL.PROGRAM.FILTERS.HTML"></a>5.1.4.&nbsp;Input
                handler output</h3>
              </div>
            </div>
          </div>
          <p>Both the simple and persistent input handlers can
          return any MIME type to Recoll, which will further
          process the data according to the MIME configuration.</p>
          <p>Most input filters filters produce either <code class=
          "literal">text/plain</code> or <code class=
          "literal">text/html</code> data. There are exceptions,
          for example, filters which process archive file
          (<code class="literal">zip</code>, <code class=
          "literal">tar</code>, etc.) will usually return the
          documents as they are found, without processing them
          further.</p>
          <p>There is nothing to say about <code class=
          "literal">text/plain</code> output, except that its
          character encoding should be consistent with what is
          specified in the <code class="filename">mimeconf</code>
          file.</p>
          <p>For filters producing HTML, the output could be very
          minimal like the following example:</p>
          <pre class="programlisting">
          &lt;html&gt;
          &lt;head&gt;
          &lt;meta http-equiv="Content-Type" content="text/html;charset=UTF-8"&gt;
          &lt;/head&gt;
          &lt;body&gt;
          Some text content
          &lt;/body&gt;
          &lt;/html&gt;
        </pre>
          <p>You should take care to escape some characters inside
          the text by transforming them into appropriate entities.
          At the very minimum, "<code class="literal">&amp;</code>"
          should be transformed into "<code class=
          "literal">&amp;amp;</code>", "<code class=
          "literal">&lt;</code>" should be transformed into
          "<code class="literal">&amp;lt;</code>". This is not
          always properly done by external helper programs which
          output HTML, and of course never by those which output
          plain text.</p>
          <p>When encapsulating plain text in an HTML body, the
          display of a preview may be improved by enclosing the
          text inside <code class="literal">&lt;pre&gt;</code>
          tags.</p>
          <p>The character set needs to be specified in the header.
          It does not need to be UTF-8 (<span class=
          "application">Recoll</span> will take care of translating
          it), but it must be accurate for good results.</p>
          <p><span class="application">Recoll</span> will process
          <code class="literal">meta</code> tags inside the header
          as possible document fields candidates. Documents fields
          can be processed by the indexer in different ways, for
          searching or displaying inside query results. This is
          described in a <a class="link" href="#RCL.PROGRAM.FIELDS"
          title="5.2.&nbsp;Field data processing">following
          section.</a></p>
          <p>By default, the indexer will process the standard
          header fields if they are present: <code class=
          "literal">title</code>, <code class=
          "literal">meta/description</code>, and <code class=
          "literal">meta/keywords</code> are both indexed and
          stored for query-time display.</p>
          <p>A predefined non-standard <code class=
          "literal">meta</code> tag will also be processed by
          <span class="application">Recoll</span> without further
          configuration: if a <code class="literal">date</code> tag
          is present and has the right format, it will be used as
          the document date (for display and sorting), in
          preference to the file modification date. The date format
          should be as follows:</p>
          <pre class="programlisting">
          &lt;meta name="date" content="YYYY-mm-dd HH:MM:SS"&gt;
          or
          &lt;meta name="date" content="YYYY-mm-ddTHH:MM:SS"&gt;
        </pre>
          <p>Example:</p>
          <pre class="programlisting">
          &lt;meta name="date" content="2013-02-24 17:50:00"&gt;
        </pre>
          <p>Input handlers also have the possibility to "invent"
          field names. This should also be output as meta tags:</p>
          <pre class="programlisting">
          &lt;meta name="somefield" content="Some textual data" /&gt;
        </pre>
          <p>You can embed HTML markup inside the content of custom
          fields, for improving the display inside result lists. In
          this case, add a (wildly non-standard) <code class=
          "literal">markup</code> attribute to tell <span class=
          "application">Recoll</span> that the value is HTML and
          should not be escaped for display.</p>
          <pre class="programlisting">
          &lt;meta name="somefield" markup="html" content="Some &lt;i&gt;textual&lt;/i&gt; data" /&gt;
        </pre>
          <p>As written above, the processing of fields is
          described in a <a class="link" href="#RCL.PROGRAM.FIELDS"
          title="5.2.&nbsp;Field data processing">further
          section</a>.</p>
          <p>Persistent filters can use another, probably simpler,
          method to produce metadata, by calling the <code class=
          "literal">setfield()</code> helper method. This avoids
          the necessity to produce HTML, and any issue with HTML
          quoting. See, for example, <code class=
          "filename">rclaudio</code> in <span class=
          "application">Recoll</span> 1.23 and later for an example
          of handler which outputs <code class=
          "literal">text/plain</code> and uses <code class=
          "literal">setfield()</code> to produce metadata.</p>
        </div>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name=
                "RCL.PROGRAM.FILTERS.PAGES" id=
                "RCL.PROGRAM.FILTERS.PAGES"></a>5.1.5.&nbsp;Page
                numbers</h3>
              </div>
            </div>
          </div>
          <p>The indexer will interpret <code class=
          "literal">^L</code> characters in the handler output as
          indicating page breaks, and will record them. At query
          time, this allows starting a viewer on the right page for
          a hit or a snippet. Currently, only the PDF, Postscript
          and DVI handlers generate page breaks.</p>
        </div>
      </div>
      <div class="sect1">
        <div class="titlepage">
          <div>
            <div>
              <h2 class="title" style="clear: both"><a name=
              "RCL.PROGRAM.FIELDS" id=
              "RCL.PROGRAM.FIELDS"></a>5.2.&nbsp;Field data
              processing</h2>
            </div>
          </div>
        </div>
        <p><code class="literal">Fields</code> are named pieces of
        information in or about documents, like <code class=
        "literal">title</code>, <code class=
        "literal">author</code>, <code class=
        "literal">abstract</code>.</p>
        <p>The field values for documents can appear in several
        ways during indexing: either output by input handlers as
        <code class="literal">meta</code> fields in the HTML header
        section, or extracted from file extended attributes, or
        added as attributes of the <code class="literal">Doc</code>
        object when using the API, or again synthetized internally
        by <span class="application">Recoll</span>.</p>
        <p>The <span class="application">Recoll</span> query
        language allows searching for text in a specific field.</p>
        <p><span class="application">Recoll</span> defines a number
        of default fields. Additional ones can be output by
        handlers, and described in the <code class=
        "filename">fields</code> configuration file.</p>
        <p>Fields can be:</p>
        <div class="itemizedlist">
          <ul class="itemizedlist" style="list-style-type: disc;">
            <li class="listitem">
              <p><code class="literal">indexed</code>, meaning that
              their terms are separately stored in inverted lists
              (with a specific prefix), and that a field-specific
              search is possible.</p>
            </li>
            <li class="listitem">
              <p><code class="literal">stored</code>, meaning that
              their value is recorded in the index data record for
              the document, and can be returned and displayed with
              search results.</p>
            </li>
          </ul>
        </div>
        <p>A field can be either or both indexed and stored. This
        and other aspects of fields handling is defined inside the
        <code class="filename">fields</code> configuration
        file.</p>
        <p>Some fields may also designated as supporting range
        queries, meaning that the results may be selected for an
        interval of its values. See the <a class="link" href=
        "#RCL.INSTALL.CONFIG.FIELDS" title=
        "6.4.3.&nbsp;The fields file">configuration section</a> for
        more details.</p>
        <p>The sequence of events for field processing is as
        follows:</p>
        <div class="itemizedlist">
          <ul class="itemizedlist" style="list-style-type: disc;">
            <li class="listitem">
              <p>During indexing, <span class=
              "command"><strong>recollindex</strong></span> scans
              all <code class="literal">meta</code> fields in HTML
              documents (most document types are transformed into
              HTML at some point). It compares the name for each
              element to the configuration defining what should be
              done with fields (the <code class=
              "filename">fields</code> file)</p>
            </li>
            <li class="listitem">
              <p>If the name for the <code class=
              "literal">meta</code> element matches one for a field
              that should be indexed, the contents are processed
              and the terms are entered into the index with the
              prefix defined in the <code class=
              "filename">fields</code> file.</p>
            </li>
            <li class="listitem">
              <p>If the name for the <code class=
              "literal">meta</code> element matches one for a field
              that should be stored, the content of the element is
              stored with the document data record, from which it
              can be extracted and displayed at query time.</p>
            </li>
            <li class="listitem">
              <p>At query time, if a field search is performed, the
              index prefix is computed and the match is only
              performed against appropriately prefixed terms in the
              index.</p>
            </li>
            <li class="listitem">
              <p>At query time, the field can be displayed inside
              the result list by using the appropriate directive in
              the definition of the <a class="link" href=
              "#RCL.SEARCH.GUI.CUSTOM.RESLIST" title=
              "3.1.15.1.&nbsp;The result list format">result list
              paragraph format</a>. All fields are displayed on the
              fields screen of the preview window (which you can
              reach through the right-click menu). This is
              independant of the fact that the search which
              produced the results used the field or not.</p>
            </li>
          </ul>
        </div>
        <p>You can find more information in the <a class="link"
        href="#RCL.INSTALL.CONFIG.FIELDS" title=
        "6.4.3.&nbsp;The fields file">section about the
        <code class="filename">fields</code> file</a>, or in
        comments inside the file.</p>
        <p>You can also have a look at the <a class="ulink" href=
        "https://www.lesbonscomptes.com/recoll/faqsandhowtos/HandleCustomField"
        target="_top">example in the FAQs area</a>, detailing how
        one could add a <span class="emphasis"><em>page
        count</em></span> field to pdf documents for displaying
        inside result lists.</p>
      </div>
      <div class="sect1">
        <div class="titlepage">
          <div>
            <div>
              <h2 class="title" style="clear: both"><a name=
              "RCL.PROGRAM.PYTHONAPI" id=
              "RCL.PROGRAM.PYTHONAPI"></a>5.3.&nbsp;Python API</h2>
            </div>
          </div>
        </div>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name=
                "RCL.PROGRAM.PYTHONAPI.INTRO" id=
                "RCL.PROGRAM.PYTHONAPI.INTRO"></a>5.3.1.&nbsp;Introduction</h3>
              </div>
            </div>
          </div>
          <p><span class="application">Recoll</span> versions after
          1.11 define a Python programming interface, both for
          searching and creating/updating an index.</p>
          <p>The search interface is used in the <span class=
          "application">Recoll</span> Ubuntu Unity Lens and the
          <span class="application">Recoll</span> Web UI. It can
          run queries on any <span class=
          "application">Recoll</span> configuration.</p>
          <p>The index update section of the API may be used to
          create and update <span class="application">Recoll</span>
          indexes on specific configurations (separate from the
          ones created by <span class=
          "command"><strong>recollindex</strong></span>). The
          resulting databases can be queried alone, or in
          conjunction with regular ones, through the GUI or any of
          the query interfaces.</p>
          <p>The search API is modeled along the Python database
          API specification. There were two major changes along
          <span class="application">Recoll</span> versions:</p>
          <div class="itemizedlist">
            <ul class="itemizedlist" style=
            "list-style-type: disc;">
              <li class="listitem">
                <p>The basis for the <span class=
                "application">Recoll</span> API changed from Python
                database API version 1.0 (<span class=
                "application">Recoll</span> versions up to 1.18.1),
                to version 2.0 (<span class=
                "application">Recoll</span> 1.18.2 and later).</p>
              </li>
              <li class="listitem">
                <p>The <code class="literal">recoll</code> module
                became a package (with an internal <code class=
                "literal">recoll</code> module) as of <span class=
                "application">Recoll</span> version 1.19, in order
                to add more functions. For existing code, this only
                changes the way the interface must be imported.</p>
              </li>
            </ul>
          </div>
          <p>We will describe the new API and package structure
          here. A paragraph at the end of this section will explain
          a few differences and ways to write code compatible with
          both versions.</p>
          <p>There is a good chance that your system repository has
          packages for the Recoll Python API, sometimes in a
          package separate from the main one (maybe named something
          like python-recoll). Else refer to the <a class="link"
          href="#RCL.INSTALL.BUILDING" title=
          "6.3.&nbsp;Building from source">Building from source
          chapter</a>.</p>
          <p>As an introduction, the following small sample will
          run a query and list the title and url for each of the
          results. It would work with <span class=
          "application">Recoll</span> 1.19 and later. The
          <code class="filename">python/samples</code> source
          directory contains several examples of Python programming
          with <span class="application">Recoll</span>, exercising
          the extension more completely, and especially its data
          extraction features.</p>
          <pre class="programlisting">
        #!/usr/bin/env python

        from recoll import recoll

        db = recoll.connect()
        query = db.query()
        nres = query.execute("some query")
        results = query.fetchmany(20)
        for doc in results:
        print(doc.url, doc.title)
        </pre>
          <p>You can also take a look at the source for the
          <a class="ulink" href=
          "https://github.com/koniu/recoll-webui" target=
          "_top">Recoll WebUI</a>, or the <a class="ulink" href=
          "https://opensourceprojects.eu/p/upmpdcli/code/ci/c8c8e75bd181ad9db2df14da05934e53ca867a06/tree/src/mediaserver/cdplugins/uprcl/uprclfolders.py"
          target="_top">upmpdcli local media server</a>, which are
          both based on the Python API.</p>
        </div>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name=
                "RCL.PROGRAM.PYTHONAPI.ELEMENTS" id=
                "RCL.PROGRAM.PYTHONAPI.ELEMENTS"></a>5.3.2.&nbsp;Interface
                elements</h3>
              </div>
            </div>
          </div>
          <p>A few elements in the interface are specific and and
          need an explanation.</p>
          <div class="variablelist">
            <dl class="variablelist">
              <dt><a name="RCL.PROGRAM.PYTHONAPI.ELEMENTS.IPATH"
              id="RCL.PROGRAM.PYTHONAPI.ELEMENTS.IPATH"></a><span class="term">ipath</span></dt>
              <dd>
                <p>This data value (set as a field in the Doc
                object) is stored, along with the URL, but not
                indexed by <span class="application">Recoll</span>.
                Its contents are not interpreted by the index
                layer, and its use is up to the application. For
                example, the <span class=
                "application">Recoll</span> file system indexer
                uses the <code class="literal">ipath</code> to
                store the part of the document access path internal
                to (possibly imbricated) container documents.
                <code class="literal">ipath</code> in this case is
                a vector of access elements (e.g, the first part
                could be a path inside a zip file to an archive
                member which happens to be an mbox file, the second
                element would be the message sequential number
                inside the mbox etc.). <code class=
                "literal">url</code> and <code class=
                "literal">ipath</code> are returned in every search
                result and define the access to the original
                document. <code class="literal">ipath</code> is
                empty for top-level document/files (e.g. a PDF
                document which is a filesystem file). The
                <span class="application">Recoll</span> GUI knows
                about the structure of the <code class=
                "literal">ipath</code> values used by the
                filesystem indexer, and uses it for such functions
                as opening the parent of a given document.</p>
              </dd>
              <dt><a name="RCL.PROGRAM.PYTHONAPI.ELEMENTS.UDI" id=
              "RCL.PROGRAM.PYTHONAPI.ELEMENTS.UDI"></a><span class=
              "term">udi</span></dt>
              <dd>
                <p>An <code class="literal">udi</code> (unique
                document identifier) identifies a document. Because
                of limitations inside the index engine, it is
                restricted in length (to 200 bytes), which is why a
                regular URI cannot be used. The structure and
                contents of the <code class="literal">udi</code> is
                defined by the application and opaque to the index
                engine. For example, the internal file system
                indexer uses the complete document path (file path
                + internal path), truncated to length, the
                suppressed part being replaced by a hash value. The
                <code class="literal">udi</code> is not explicit in
                the query interface (it is used "under the hood" by
                the <code class="filename">rclextract</code>
                module), but it is an explicit element of the
                update interface.</p>
              </dd>
              <dt><a name=
              "RCL.PROGRAM.PYTHONAPI.ELEMENTS.PARENTUDI" id=
              "RCL.PROGRAM.PYTHONAPI.ELEMENTS.PARENTUDI"></a><span class="term">parent_udi</span></dt>
              <dd>
                <p>If this attribute is set on a document when
                entering it in the index, it designates its
                physical container document. In a multilevel
                hierarchy, this may not be the immediate parent.
                <code class="literal">parent_udi</code> is
                optional, but its use by an indexer may simplify
                index maintenance, as <span class=
                "application">Recoll</span> will automatically
                delete all children defined by <code class=
                "literal">parent_udi == udi</code> when the
                document designated by <code class=
                "literal">udi</code> is destroyed. e.g. if a
                <code class="literal">Zip</code> archive contains
                entries which are themselves containers, like
                <code class="literal">mbox</code> files, all the
                subdocuments inside the <code class=
                "literal">Zip</code> file (mbox, messages, message
                attachments, etc.) would have the same <code class=
                "literal">parent_udi</code>, matching the
                <code class="literal">udi</code> for the
                <code class="literal">Zip</code> file, and all
                would be destroyed when the <code class=
                "literal">Zip</code> file (identified by its
                <code class="literal">udi</code>) is removed from
                the index. The standard filesystem indexer uses
                <code class="literal">parent_udi</code>.</p>
              </dd>
              <dt><span class="term">Stored and indexed
              fields</span></dt>
              <dd>
                <p>The <code class="filename">fields</code> file
                inside the <span class="application">Recoll</span>
                configuration defines which document fields are
                either "indexed" (searchable), "stored"
                (retrievable with search results), or both.</p>
              </dd>
            </dl>
          </div>
        </div>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name=
                "RCL.PROGRAM.PYTHONAPI.SEARCH" id=
                "RCL.PROGRAM.PYTHONAPI.SEARCH"></a>5.3.3.&nbsp;Python
                search interface</h3>
              </div>
            </div>
          </div>
          <div class="sect3">
            <div class="titlepage">
              <div>
                <div>
                  <h4 class="title"><a name=
                  "RCL.PROGRAM.PYTHONAPI.PACKAGE" id=
                  "RCL.PROGRAM.PYTHONAPI.PACKAGE"></a>5.3.3.1.&nbsp;Recoll
                  package</h4>
                </div>
              </div>
            </div>
            <p>The <code class="literal">recoll</code> package
            contains two modules:</p>
            <div class="itemizedlist">
              <ul class="itemizedlist" style=
              "list-style-type: disc;">
                <li class="listitem">
                  <p>The <code class="literal">recoll</code> module
                  contains functions and classes used to query (or
                  update) the index. This section will only
                  describe the query part, see further for the
                  update part.</p>
                </li>
                <li class="listitem">
                  <p>The <code class="literal">rclextract</code>
                  module contains functions and classes used to
                  access document data.</p>
                </li>
              </ul>
            </div>
          </div>
          <div class="sect3">
            <div class="titlepage">
              <div>
                <div>
                  <h4 class="title"><a name=
                  "RCL.PROGRAM.PYTHONAPI.RECOLL" id=
                  "RCL.PROGRAM.PYTHONAPI.RECOLL"></a>5.3.3.2.&nbsp;The
                  recoll module</h4>
                </div>
              </div>
            </div>
            <div class="sect4">
              <div class="titlepage">
                <div>
                  <div>
                    <h5 class="title"><a name=
                    "RCL.PROGRAM.PYTHONAPI.RECOLL.FUNCTIONS" id=
                    "RCL.PROGRAM.PYTHONAPI.RECOLL.FUNCTIONS"></a>Functions</h5>
                  </div>
                </div>
              </div>
              <div class="variablelist">
                <dl class="variablelist">
                  <dt><span class="term">connect(confdir=None,
                  extra_dbs=None, writable = False)</span></dt>
                  <dd>
                    <p>The <code class="literal">connect()</code>
                    function connects to one or several
                    <span class="application">Recoll</span>
                    index(es) and returns a <code class=
                    "literal">Db</code> object.</p>
                    <div class="itemizedlist">
                      <ul class="itemizedlist" style=
                      "list-style-type: disc;">
                        <li class="listitem">
                          <p><code class="literal">confdir</code>
                          may specify a configuration directory.
                          The usual defaults apply.</p>
                        </li>
                        <li class="listitem">
                          <p><code class="literal">extra_dbs</code>
                          is a list of additional indexes (Xapian
                          directories).</p>
                        </li>
                        <li class="listitem">
                          <p><code class="literal">writable</code>
                          decides if we can index new data through
                          this connection.</p>
                        </li>
                      </ul>
                    </div>
                    <p>This call initializes the recoll module, and
                    it should always be performed before any other
                    call or object creation.</p>
                  </dd>
                </dl>
              </div>
            </div>
            <div class="sect4">
              <div class="titlepage">
                <div>
                  <div>
                    <h5 class="title"><a name=
                    "RCL.PROGRAM.PYTHONAPI.RECOLL.CLASSES" id=
                    "RCL.PROGRAM.PYTHONAPI.RECOLL.CLASSES"></a>Classes</h5>
                  </div>
                </div>
              </div>
              <div class="sect5">
                <div class="titlepage">
                  <div>
                    <div>
                      <h6 class="title"><a name=
                      "RCL.PROGRAM.PYTHONAPI.RECOLL.CLASSES.DB" id=
                      "RCL.PROGRAM.PYTHONAPI.RECOLL.CLASSES.DB"></a>The
                      Db class</h6>
                    </div>
                  </div>
                </div>
                <p>A Db object is created by a <code class=
                "literal">connect()</code> call and holds a
                connection to a Recoll index.</p>
                <div class="variablelist">
                  <dl class="variablelist">
                    <dt><span class="term">Db.close()</span></dt>
                    <dd>
                      <p>Closes the connection. You can't do
                      anything with the <code class=
                      "literal">Db</code> object after this.</p>
                    </dd>
                    <dt><span class="term">Db.query(),
                    Db.cursor()</span></dt>
                    <dd>
                      <p>These aliases return a blank <code class=
                      "literal">Query</code> object for this
                      index.</p>
                    </dd>
                    <dt><span class=
                    "term">Db.setAbstractParams(maxchars,
                    contextwords)</span></dt>
                    <dd>
                      <p>Set the parameters used to build snippets
                      (sets of keywords in context text fragments).
                      <code class="literal">maxchars</code> defines
                      the maximum total size of the abstract.
                      <code class="literal">contextwords</code>
                      defines how many terms are shown around the
                      keyword.</p>
                    </dd>
                    <dt><span class="term">Db.termMatch(match_type,
                    expr, field='', maxlen=-1, casesens=False,
                    diacsens=False, lang='english')</span></dt>
                    <dd>
                      <p>Expand an expression against the index
                      term list. Performs the basic function from
                      the GUI term explorer tool. <code class=
                      "literal">match_type</code> can be either of
                      <code class="literal">wildcard</code>,
                      <code class="literal">regexp</code> or
                      <code class="literal">stem</code>. Returns a
                      list of terms expanded from the input
                      expression.</p>
                    </dd>
                  </dl>
                </div>
              </div>
              <div class="sect5">
                <div class="titlepage">
                  <div>
                    <div>
                      <h6 class="title"><a name=
                      "RCL.PROGRAM.PYTHONAPI.RECOLL.CLASSES.QUERY"
                      id=
                      "RCL.PROGRAM.PYTHONAPI.RECOLL.CLASSES.QUERY"></a>The
                      Query class</h6>
                    </div>
                  </div>
                </div>
                <p>A <code class="literal">Query</code> object
                (equivalent to a cursor in the Python DB API) is
                created by a <code class=
                "literal">Db.query()</code> call. It is used to
                execute index searches.</p>
                <div class="variablelist">
                  <dl class="variablelist">
                    <dt><span class="term">Query.sortby(fieldname,
                    ascending=True)</span></dt>
                    <dd>
                      <p>Sort results by <em class=
                      "replaceable"><code>fieldname</code></em>, in
                      ascending or descending order. Must be called
                      before executing the search.</p>
                    </dd>
                    <dt><span class=
                    "term">Query.execute(query_string, stemming=1,
                    stemlang="english",
                    fetchtext=False)</span></dt>
                    <dd>
                      <p>Starts a search for <em class=
                      "replaceable"><code>query_string</code></em>,
                      a <span class="application">Recoll</span>
                      search language string. If the index stores
                      the document texts and <code class=
                      "literal">fetchtext</code> is True, store the
                      document extracted text in <code class=
                      "literal">doc.text</code>.</p>
                    </dd>
                    <dt><span class=
                    "term">Query.executesd(SearchData,
                    fetchtext=False)</span></dt>
                    <dd>
                      <p>Starts a search for the query defined by
                      the SearchData object. If the index stores
                      the document texts and <code class=
                      "literal">fetchtext</code> is True, store the
                      document extracted text in <code class=
                      "literal">doc.text</code>.</p>
                    </dd>
                    <dt><span class=
                    "term">Query.fetchmany(size=query.arraysize)</span></dt>
                    <dd>
                      <p>Fetches the next <code class=
                      "literal">Doc</code> objects in the current
                      search results, and returns them as an array
                      of the required size, which is by default the
                      value of the <code class=
                      "literal">arraysize</code> data member.</p>
                    </dd>
                    <dt><span class=
                    "term">Query.fetchone()</span></dt>
                    <dd>
                      <p>Fetches the next <code class=
                      "literal">Doc</code> object from the current
                      search results. Generates a StopIteration
                      exception if there are no results left.</p>
                    </dd>
                    <dt><span class=
                    "term">Query.close()</span></dt>
                    <dd>
                      <p>Closes the query. The object is unusable
                      after the call.</p>
                    </dd>
                    <dt><span class="term">Query.scroll(value,
                    mode='relative')</span></dt>
                    <dd>
                      <p>Adjusts the position in the current result
                      set. <code class="literal">mode</code> can be
                      <code class="literal">relative</code> or
                      <code class="literal">absolute</code>.</p>
                    </dd>
                    <dt><span class=
                    "term">Query.getgroups()</span></dt>
                    <dd>
                      <p>Retrieves the expanded query terms as a
                      list of pairs. Meaningful only after
                      executexx In each pair, the first entry is a
                      list of user terms (of size one for simple
                      terms, or more for group and phrase clauses),
                      the second a list of query terms as derived
                      from the user terms and used in the Xapian
                      Query.</p>
                    </dd>
                    <dt><span class=
                    "term">Query.getxquery()</span></dt>
                    <dd>
                      <p>Return the Xapian query description as a
                      Unicode string. Meaningful only after
                      executexx.</p>
                    </dd>
                    <dt><span class="term">Query.highlight(text,
                    ishtml = 0, methods = object)</span></dt>
                    <dd>
                      <p>Will insert &lt;span "class=rclmatch"&gt;,
                      &lt;/span&gt; tags around the match areas in
                      the input text and return the modified text.
                      <code class="literal">ishtml</code> can be
                      set to indicate that the input text is HTML
                      and that HTML special characters should not
                      be escaped. <code class=
                      "literal">methods</code> if set should be an
                      object with methods startMatch(i) and
                      endMatch() which will be called for each
                      match and should return a begin and end
                      tag</p>
                    </dd>
                    <dt><span class=
                    "term">Query.makedocabstract(doc, methods =
                    object))</span></dt>
                    <dd>
                      <p>Create a snippets abstract for
                      <code class="literal">doc</code> (a
                      <code class="literal">Doc</code> object) by
                      selecting text around the match terms. If
                      methods is set, will also perform
                      highlighting. See the highlight method.</p>
                    </dd>
                    <dt><span class="term">Query.__iter__() and
                    Query.next()</span></dt>
                    <dd>
                      <p>So that things like <code class=
                      "literal">for doc in query:</code> will
                      work.</p>
                    </dd>
                  </dl>
                </div>
                <div class="variablelist">
                  <dl class="variablelist">
                    <dt><span class=
                    "term">Query.arraysize</span></dt>
                    <dd>
                      <p>Default number of records processed by
                      fetchmany (r/w).</p>
                    </dd>
                    <dt><span class=
                    "term">Query.rowcount</span></dt>
                    <dd>
                      <p>Number of records returned by the last
                      execute.</p>
                    </dd>
                    <dt><span class=
                    "term">Query.rownumber</span></dt>
                    <dd>
                      <p>Next index to be fetched from results.
                      Normally increments after each fetchone()
                      call, but can be set/reset before the call to
                      effect seeking (equivalent to using
                      <code class="literal">scroll()</code>).
                      Starts at 0.</p>
                    </dd>
                  </dl>
                </div>
              </div>
              <div class="sect5">
                <div class="titlepage">
                  <div>
                    <div>
                      <h6 class="title"><a name=
                      "RCL.PROGRAM.PYTHONAPI.RECOLL.CLASSES.DOC"
                      id="RCL.PROGRAM.PYTHONAPI.RECOLL.CLASSES.DOC">
                      </a>The Doc class</h6>
                    </div>
                  </div>
                </div>
                <p>A <code class="literal">Doc</code> object
                contains index data for a given document. The data
                is extracted from the index when searching, or set
                by the indexer program when updating. The Doc
                object has many attributes to be read or set by its
                user. It matches exactly the Rcl::Doc C++ object.
                Some of the attributes are predefined, but,
                especially when indexing, others can be set, the
                name of which will be processed as field names by
                the indexing configuration. Inputs can be specified
                as Unicode or strings. Outputs are Unicode objects.
                All dates are specified as Unix timestamps, printed
                as strings. Please refer to the <code class=
                "filename">rcldb/rcldoc.h</code> C++ file for a
                description of the predefined attributes.</p>
                <p>At query time, only the fields that are defined
                as <code class="literal">stored</code> either by
                default or in the <code class=
                "filename">fields</code> configuration file will be
                meaningful in the <code class="literal">Doc</code>
                object. Especially this will not be the case for
                the document text. See the <code class=
                "literal">rclextract</code> module for accessing
                document contents.</p>
                <div class="variablelist">
                  <dl class="variablelist">
                    <dt><span class="term">get(key), []
                    operator</span></dt>
                    <dd>
                      <p>Retrieve the named doc attribute. You can
                      also use <code class="literal">getattr(doc,
                      key)</code> or <code class=
                      "literal">doc.key</code>.</p>
                    </dd>
                    <dt><span class="term">doc.key =
                    value</span></dt>
                    <dd>
                      <p>Set the the named doc attribute. You can
                      also use <code class="literal">setattr(doc,
                      key, value)</code>.</p>
                    </dd>
                    <dt><span class="term">getbinurl()</span></dt>
                    <dd>
                      <p>Retrieve the URL in byte array format (no
                      transcoding), for use as parameter to a
                      system call.</p>
                    </dd>
                    <dt><span class=
                    "term">setbinurl(url)</span></dt>
                    <dd>
                      <p>Set the URL in byte array format (no
                      transcoding).</p>
                    </dd>
                    <dt><span class="term">items()</span></dt>
                    <dd>
                      <p>Return a dictionary of doc object
                      keys/values</p>
                    </dd>
                    <dt><span class="term">keys()</span></dt>
                    <dd>
                      <p>list of doc object keys (attribute
                      names).</p>
                    </dd>
                  </dl>
                </div>
              </div>
              <div class="sect5">
                <div class="titlepage">
                  <div>
                    <div>
                      <h6 class="title"><a name=
                      "RCL.PROGRAM.PYTHONAPI.RECOLL.CLASSES.SEARCHDATA"
                      id=
                      "RCL.PROGRAM.PYTHONAPI.RECOLL.CLASSES.SEARCHDATA">
                      </a>The SearchData class</h6>
                    </div>
                  </div>
                </div>
                <p>A <code class="literal">SearchData</code> object
                allows building a query by combining clauses, for
                execution by <code class=
                "literal">Query.executesd()</code>. It can be used
                in replacement of the query language approach. The
                interface is going to change a little, so no
                detailed doc for now...</p>
                <div class="variablelist">
                  <dl class="variablelist">
                    <dt><span class=
                    "term">addclause(type='and'|'or'|'excl'|'phrase'|'near'|'sub',
                    qstring=string, slack=0, field='', stemming=1,
                    subSearch=SearchData)</span></dt>
                    <dd></dd>
                  </dl>
                </div>
              </div>
            </div>
          </div>
          <div class="sect3">
            <div class="titlepage">
              <div>
                <div>
                  <h4 class="title"><a name=
                  "RCL.PROGRAM.PYTHONAPI.RCLEXTRACT" id=
                  "RCL.PROGRAM.PYTHONAPI.RCLEXTRACT"></a>5.3.3.3.&nbsp;The
                  rclextract module</h4>
                </div>
              </div>
            </div>
            <p>Prior to <span class="application">Recoll</span>
            1.25, index queries never provide document content
            because it is not stored. More recent versions usually
            store the document text, which can be optionally
            retrieved when running a query (see <code class=
            "literal">query.execute()</code> above - the result is
            always plain text).</p>
            <p>The <code class="literal">rclextract</code> module
            can give access to the original document and to the
            document text content (if not stored by the index, or
            to access an HTML version of the text). Acessing the
            original document is particularly useful if it is
            embedded (e.g. an email attachment).</p>
            <p>You need to import the <code class=
            "literal">recoll</code> module before the <code class=
            "literal">rclextract</code> module.</p>
            <div class="sect4">
              <div class="titlepage">
                <div>
                  <div>
                    <h5 class="title"><a name=
                    "RCL.PROGRAM.PYTHONAPI.RCLEXTRACT.CLASSES.EXTRACTOR"
                    id=
                    "RCL.PROGRAM.PYTHONAPI.RCLEXTRACT.CLASSES.EXTRACTOR">
                    </a>The Extractor class</h5>
                  </div>
                </div>
              </div>
              <div class="variablelist">
                <dl class="variablelist">
                  <dt><span class="term">Extractor(doc)</span></dt>
                  <dd>
                    <p>An <code class="literal">Extractor</code>
                    object is built from a <code class=
                    "literal">Doc</code> object, output from a
                    query.</p>
                  </dd>
                  <dt><span class=
                  "term">Extractor.textextract(ipath)</span></dt>
                  <dd>
                    <p>Extract document defined by <em class=
                    "replaceable"><code>ipath</code></em> and
                    return a <code class="literal">Doc</code>
                    object. The <code class=
                    "literal">doc.text</code> field has the
                    document text converted to either text/plain or
                    text/html according to <code class=
                    "literal">doc.mimetype</code>. The typical use
                    would be as follows:</p>
                    <pre class="programlisting">
from recoll import recoll, rclextract

qdoc = query.fetchone()
extractor = recoll.Extractor(qdoc)
doc = extractor.textextract(qdoc.ipath)
# use doc.text, e.g. for previewing</pre>
                    <p>Passing <code class=
                    "literal">qdoc.ipath</code> to <code class=
                    "literal">textextract()</code> is redundant,
                    but reflects the fact that the <code class=
                    "literal">Extractor</code> object actually has
                    the capability to access the other entries in a
                    compound document.</p>
                  </dd>
                  <dt><span class=
                  "term">Extractor.idoctofile(ipath, targetmtype,
                  outfile='')</span></dt>
                  <dd>
                    <p>Extracts document into an output file, which
                    can be given explicitly or will be created as a
                    temporary file to be deleted by the caller.
                    Typical use:</p>
                    <pre class="programlisting">
from recoll import recoll, rclextract

qdoc = query.fetchone()
extractor = recoll.Extractor(qdoc)
filename = extractor.idoctofile(qdoc.ipath, qdoc.mimetype)</pre>
                    <p>In all cases the output is a copy, even if
                    the requested document is a regular system
                    file, which may be wasteful in some cases. If
                    you want to avoid this, you can test for a
                    simple file document as follows:</p>
                    <pre class="programlisting">
not doc.ipath and (not "rclbes" in doc.keys() or doc["rclbes"] == "FS")
</pre>
                  </dd>
                </dl>
              </div>
            </div>
          </div>
          <div class="sect3">
            <div class="titlepage">
              <div>
                <div>
                  <h4 class="title"><a name=
                  "RCL.PROGRAM.PYTHONAPI.SEARCH.EXAMPLE" id=
                  "RCL.PROGRAM.PYTHONAPI.SEARCH.EXAMPLE"></a>5.3.3.4.&nbsp;Search
                  API usage example</h4>
                </div>
              </div>
            </div>
            <p>The following sample would query the index with a
            user language string. See the <code class=
            "filename">python/samples</code> directory inside the
            <span class="application">Recoll</span> source for
            other examples. The <code class=
            "filename">recollgui</code> subdirectory has a very
            embryonic GUI which demonstrates the highlighting and
            data extraction functions.</p>
            <pre class="programlisting">
#!/usr/bin/env python

from recoll import recoll

db = recoll.connect()
db.setAbstractParams(maxchars=80, contextwords=4)

query = db.query()
nres = query.execute("some user question")
print "Result count: ", nres
if nres &gt; 5:
    nres = 5
for i in range(nres):
    doc = query.fetchone()
    print "Result #%d" % (query.rownumber,)
    for k in ("title", "size"):
        print k, ":", getattr(doc, k).encode('utf-8')
    abs = db.makeDocAbstract(doc, query).encode('utf-8')
    print abs
    print
</pre>
          </div>
        </div>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name=
                "RCL.PROGRAM.PYTHONAPI.UPDATE" id=
                "RCL.PROGRAM.PYTHONAPI.UPDATE"></a>5.3.4.&nbsp;Creating
                Python external indexers</h3>
              </div>
            </div>
          </div>
          <p>The update API can be used to create an index from
          data which is not accessible to the regular <span class=
          "application">Recoll</span> indexer, or structured to
          present difficulties to the <span class=
          "application">Recoll</span> input handlers.</p>
          <p>An indexer created using this API will be have
          equivalent work to do as the the Recoll file system
          indexer: look for modified documents, extract their text,
          call the API for indexing it, take care of purging the
          index out of data from documents which do not exist in
          the document store any more.</p>
          <p>The data for such an external indexer should be stored
          in an index separate from any used by the <span class=
          "application">Recoll</span> internal file system indexer.
          The reason is that the main document indexer purge pass
          (removal of deleted documents) would also remove all the
          documents belonging to the external indexer, as they were
          not seen during the filesystem walk. The main indexer
          documents would also probably be a problem for the
          external indexer own purge operation.</p>
          <p>While there would be ways to enable multiple foreign
          indexers to cooperate on a single index, it is just
          simpler to use separate ones, and use the multiple index
          access capabilities of the query interface, if
          needed.</p>
          <p>There are two parts in the update interface:</p>
          <div class="itemizedlist">
            <ul class="itemizedlist" style=
            "list-style-type: disc;">
              <li class="listitem">
                <p>Methods inside the <code class=
                "filename">recoll</code> module allow inserting
                data into the index, to make it accessible by the
                normal query interface.</p>
              </li>
              <li class="listitem">
                <p>An interface based on scripts execution is
                defined to allow either the GUI or the <code class=
                "filename">rclextract</code> module to access
                original document data for previewing or
                editing.</p>
              </li>
            </ul>
          </div>
          <div class="sect3">
            <div class="titlepage">
              <div>
                <div>
                  <h4 class="title"><a name=
                  "RCL.PROGRAM.PYTHONAPI.UPDATE.UPDATE" id=
                  "RCL.PROGRAM.PYTHONAPI.UPDATE.UPDATE"></a>5.3.4.1.&nbsp;Python
                  update interface</h4>
                </div>
              </div>
            </div>
            <p>The update methods are part of the <code class=
            "filename">recoll</code> module described above. The
            connect() method is used with a <code class=
            "literal">writable=true</code> parameter to obtain a
            writable <code class="literal">Db</code> object. The
            following <code class="literal">Db</code> object
            methods are then available.</p>
            <div class="variablelist">
              <dl class="variablelist">
                <dt><span class="term">addOrUpdate(udi, doc,
                parent_udi=None)</span></dt>
                <dd>
                  <p>Add or update index data for a given document
                  The <code class="literal"><a class="link" href=
                  "#RCL.PROGRAM.PYTHONAPI.ELEMENTS.UDI">udi</a></code>
                  string must define a unique id for the document.
                  It is an opaque interface element and not
                  interpreted inside Recoll. <code class=
                  "literal">doc</code> is a <code class=
                  "literal"><a class="link" href=
                  "#RCL.PROGRAM.PYTHONAPI.RECOLL.CLASSES.DOC"
                  title="The Doc class">Doc</a></code> object,
                  created from the data to be indexed (the main
                  text should be in <code class=
                  "literal">doc.text</code>). If <code class=
                  "literal"><a class="link" href=
                  "#RCL.PROGRAM.PYTHONAPI.ELEMENTS.PARENTUDI">parent_udi</a></code>
                  is set, this is a unique identifier for the
                  top-level container (e.g. for the filesystem
                  indexer, this would be the one which is an actual
                  file).</p>
                </dd>
                <dt><span class="term">delete(udi)</span></dt>
                <dd>
                  <p>Purge index from all data for <code class=
                  "literal">udi</code>, and all documents (if any)
                  which have a matrching <code class=
                  "literal">parent_udi</code>.</p>
                </dd>
                <dt><span class="term">needUpdate(udi,
                sig)</span></dt>
                <dd>
                  <p>Test if the index needs to be updated for the
                  document identified by <code class=
                  "literal">udi</code>. If this call is to be used,
                  the <code class="literal">doc.sig</code> field
                  should contain a signature value when calling
                  <code class="literal">addOrUpdate()</code>. The
                  <code class="literal">needUpdate()</code> call
                  then compares its parameter value with the stored
                  <code class="literal">sig</code> for <code class=
                  "literal">udi</code>. <code class=
                  "literal">sig</code> is an opaque value, compared
                  as a string.</p>
                  <p>The filesystem indexer uses a concatenation of
                  the decimal string values for file size and
                  update time, but a hash of the contents could
                  also be used.</p>
                  <p>As a side effect, if the return value is false
                  (the index is up to date), the call will set the
                  existence flag for the document (and any
                  subdocument defined by its <code class=
                  "literal">parent_udi</code>), so that a later
                  <code class="literal">purge()</code> call will
                  preserve them).</p>
                  <p>The use of <code class=
                  "literal">needUpdate()</code> and <code class=
                  "literal">purge()</code> is optional, and the
                  indexer may use another method for checking the
                  need to reindex or to delete stale entries.</p>
                </dd>
                <dt><span class="term">purge()</span></dt>
                <dd>
                  <p>Delete all documents that were not touched
                  during the just finished indexing pass (since
                  open-for-write). These are the documents for the
                  needUpdate() call was not performed, indicating
                  that they no longer exist in the primary storage
                  system.</p>
                </dd>
              </dl>
            </div>
          </div>
          <div class="sect3">
            <div class="titlepage">
              <div>
                <div>
                  <h4 class="title"><a name=
                  "RCL.PROGRAM.PYTHONAPI.UPDATE.ACCESS" id=
                  "RCL.PROGRAM.PYTHONAPI.UPDATE.ACCESS"></a>5.3.4.2.&nbsp;Query
                  data access for external indexers (1.23)</h4>
                </div>
              </div>
            </div>
            <p><span class="application">Recoll</span> has internal
            methods to access document data for its internal
            (filesystem) indexer. An external indexer needs to
            provide data access methods if it needs integration
            with the GUI (e.g. preview function), or support for
            the <code class="filename">rclextract</code>
            module.</p>
            <p>The index data and the access method are linked by
            the <code class="literal">rclbes</code> (recoll backend
            storage) <code class="literal">Doc</code> field. You
            should set this to a short string value identifying
            your indexer (e.g. the filesystem indexer uses either
            "FS" or an empty value, the Web history indexer uses
            "BGL").</p>
            <p>The link is actually performed inside a <code class=
            "filename">backends</code> configuration file (stored
            in the configuration directory). This defines commands
            to execute to access data from the specified indexer.
            Example, for the mbox indexing sample found in the
            Recoll source (which sets <code class=
            "literal">rclbes="MBOX"</code>):</p>
            <pre class="programlisting">[MBOX]
          fetch = /path/to/recoll/src/python/samples/rclmbox.py fetch
          makesig = path/to/recoll/src/python/samples/rclmbox.py makesig
          </pre>
            <p><code class="literal">fetch</code> and <code class=
            "literal">makesig</code> define two commands to execute
            to respectively retrieve the document text and compute
            the document signature (the example implementation uses
            the same script with different first parameters to
            perform both operations).</p>
            <p>The scripts are called with three additional
            arguments: <code class="literal">udi</code>,
            <code class="literal">url</code>, <code class=
            "literal">ipath</code>, stored with the document when
            it was indexed, and may use any or all to perform the
            requested operation. The caller expects the result data
            on <code class="literal">stdout</code>.</p>
          </div>
          <div class="sect3">
            <div class="titlepage">
              <div>
                <div>
                  <h4 class="title"><a name=
                  "RCL.PROGRAM.PYTHONAPI.UPDATE.SAMPLES" id=
                  "RCL.PROGRAM.PYTHONAPI.UPDATE.SAMPLES"></a>5.3.4.3.&nbsp;External
                  indexer samples</h4>
                </div>
              </div>
            </div>
            <p>The Recoll source tree has two samples of external
            indexers in the <code class=
            "filename">src/python/samples</code> directory. The
            more interesting one is <code class=
            "filename">rclmbox.py</code> which indexes a directory
            containing <code class="literal">mbox</code> folder
            files. It exercises most features in the update
            interface, and has a data access interface.</p>
            <p>See the comments inside the file for more
            information.</p>
          </div>
        </div>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name=
                "RCL.PROGRAM.PYTHONAPI.COMPAT" id=
                "RCL.PROGRAM.PYTHONAPI.COMPAT"></a>5.3.5.&nbsp;Package
                compatibility with the previous version</h3>
              </div>
            </div>
          </div>
          <p>The following code fragments can be used to ensure
          that code can run with both the old and the new API (as
          long as it does not use the new abilities of the new API
          of course).</p>
          <p>Adapting to the new package structure:</p>
          <pre class="programlisting">
          
                   try:
                   from recoll import recoll
                   from recoll import rclextract
                   hasextract = True
                   except:
                   import recoll
                   hasextract = False
          
        </pre>
          <p>Adapting to the change of nature of the <code class=
          "literal">next</code> <code class="literal">Query</code>
          member. The same test can be used to choose to use the
          <code class="literal">scroll()</code> method (new) or set
          the <code class="literal">next</code> value (old).</p>
          <pre class="programlisting">
          
                   rownum = query.next if type(query.next) == int else \
                   query.rownumber
          
        </pre>
        </div>
      </div>
    </div>
    <div class="chapter">
      <div class="titlepage">
        <div>
          <div>
            <h1 class="title"><a name="RCL.INSTALL" id=
            "RCL.INSTALL"></a>Chapter&nbsp;6.&nbsp;Installation and
            configuration</h1>
          </div>
        </div>
      </div>
      <div class="sect1">
        <div class="titlepage">
          <div>
            <div>
              <h2 class="title" style="clear: both"><a name=
              "RCL.INSTALL.BINARY" id=
              "RCL.INSTALL.BINARY"></a>6.1.&nbsp;Installing a
              binary copy</h2>
            </div>
          </div>
        </div>
        <p><span class="application">Recoll</span> binary copies
        are always distributed as regular packages for your system.
        They can be obtained either through the system's normal
        software distribution framework (e.g. <span class=
        "application">Debian/Ubuntu apt</span>, <span class=
        "application">FreeBSD</span> ports, etc.), or from some
        type of "backports" repository providing versions newer
        than the standard ones, or found on the <span class=
        "application">Recoll</span> WEB site in some cases. The
        most up-to-date information about Recoll packages can
        usually be found on the <a class="ulink" href=
        "http://www.recoll.org/download.html" target=
        "_top"><span class="application">Recoll</span> WEB site
        downloads page</a></p>
        <p>There used to exist another form of binary install, as
        pre-compiled source trees, but these are just less
        convenient than the packages and don't exist any more.</p>
        <p>The package management tools will usually automatically
        deal with hard dependancies for packages obtained from a
        proper package repository. You will have to deal with them
        by hand for downloaded packages (for example, when
        <span class="command"><strong>dpkg</strong></span>
        complains about missing dependancies).</p>
        <p>In all cases, you will have to check or install
        <a class="link" href="#RCL.INSTALL.EXTERNAL" title=
        "6.2.&nbsp;Supporting packages">supporting applications</a>
        for the file types that you want to index beyond those that
        are natively processed by <span class=
        "application">Recoll</span> (text, HTML, email files, and a
        few others).</p>
        <p>You should also maybe have a look at the <a class="link"
        href="#RCL.INSTALL.CONFIG" title=
        "6.4.&nbsp;Configuration overview">configuration
        section</a> (but this may not be necessary for a quick test
        with default parameters). Most parameters can be more
        conveniently set from the GUI interface.</p>
      </div>
      <div class="sect1">
        <div class="titlepage">
          <div>
            <div>
              <h2 class="title" style="clear: both"><a name=
              "RCL.INSTALL.EXTERNAL" id=
              "RCL.INSTALL.EXTERNAL"></a>6.2.&nbsp;Supporting
              packages</h2>
            </div>
          </div>
        </div>
        <div class="note" style=
        "margin-left: 0.5in; margin-right: 0.5in;">
          <h3 class="title">Note</h3>
          <p>The <span class="application">Windows</span>
          installation of <span class="application">Recoll</span>
          is self-contained, and only needs Python 2.7 to be
          externally installed. <span class=
          "application">Windows</span> users can skip this
          section.</p>
        </div>
        <p><span class="application">Recoll</span> uses external
        applications to index some file types. You need to install
        them for the file types that you wish to have indexed
        (these are run-time optional dependencies. None is needed
        for building or running <span class=
        "application">Recoll</span> except for indexing their
        specific file type).</p>
        <p>After an indexing pass, the commands that were found
        missing can be displayed from the <span class=
        "command"><strong>recoll</strong></span> <span class=
        "guilabel">File</span> menu. The list is stored in the
        <code class="filename">missing</code> text file inside the
        configuration directory.</p>
        <p>A list of common file types which need external commands
        follows. Many of the handlers need the <span class=
        "command"><strong>iconv</strong></span> command, which is
        not always listed as a dependancy.</p>
        <p>Please note that, due to the relatively dynamic nature
        of this information, the most up to date version is now
        kept on <a class="ulink" href=
        "http://www.recoll.org/features.html#doctypes" target=
        "_top">http://www.recoll.org/features.html</a> along with
        links to the home pages or best source/patches pages, and
        misc tips. The list below is not updated often and may be
        quite stale.</p>
        <p>For many Linux distributions, most of the commands
        listed can be installed from the package repositories.
        However, the packages are sometimes outdated, or not the
        best version for <span class="application">Recoll</span>,
        so you should take a look at <a class="ulink" href=
        "http://www.recoll.org/features.html#doctypes" target=
        "_top">http://www.recoll.org/features.html</a> if a file
        type is important to you.</p>
        <p>As of <span class="application">Recoll</span> release
        1.14, a number of XML-based formats that were handled by ad
        hoc handler code now use the <span class=
        "command"><strong>xsltproc</strong></span> command, which
        usually comes with <span class=
        "application">libxslt</span>. These are: abiword, fb2
        (ebooks), kword, openoffice, svg.</p>
        <p>Now for the list:</p>
        <div class="itemizedlist">
          <ul class="itemizedlist" style="list-style-type: disc;">
            <li class="listitem">
              <p>Openoffice files need <span class=
              "command"><strong>unzip</strong></span> and
              <span class=
              "command"><strong>xsltproc</strong></span>.</p>
            </li>
            <li class="listitem">
              <p>PDF files need <span class=
              "command"><strong>pdftotext</strong></span> which is
              part of <span class="application">Poppler</span>
              (usually comes with the <code class=
              "literal">poppler-utils</code> package). Avoid the
              original one from <span class=
              "application">Xpdf</span>.</p>
            </li>
            <li class="listitem">
              <p>Postscript files need <span class=
              "command"><strong>pstotext</strong></span>. The
              original version has an issue with shell character in
              file names, which is corrected in recent packages.
              See <a class="ulink" href=
              "http://www.recoll.org/features.html#doctypes"
              target="_top">http://www.recoll.org/features.html</a>
              for more detail.</p>
            </li>
            <li class="listitem">
              <p>MS Word needs <span class=
              "command"><strong>antiword</strong></span>. It is
              also useful to have <span class=
              "command"><strong>wvWare</strong></span> installed as
              it may be be used as a fallback for some files which
              <span class=
              "command"><strong>antiword</strong></span> does not
              handle.</p>
            </li>
            <li class="listitem">
              <p>MS Excel and PowerPoint are processed by internal
              <span class="command"><strong>Python</strong></span>
              handlers.</p>
            </li>
            <li class="listitem">
              <p>MS Open XML (docx) needs <span class=
              "command"><strong>xsltproc</strong></span>.</p>
            </li>
            <li class="listitem">
              <p>Wordperfect files need <span class=
              "command"><strong>wpd2html</strong></span> from the
              <span class="application">libwpd</span> (or
              <span class="application">libwpd-tools</span> on
              Ubuntu) package.</p>
            </li>
            <li class="listitem">
              <p>RTF files need <span class=
              "command"><strong>unrtf</strong></span>, which, in
              its older versions, has much trouble with non-western
              character sets. Many Linux distributions carry
              outdated <span class=
              "command"><strong>unrtf</strong></span> versions.
              Check <a class="ulink" href=
              "http://www.recoll.org/features.html#doctypes"
              target="_top">http://www.recoll.org/features.html</a>
              for details.</p>
            </li>
            <li class="listitem">
              <p>TeX files need <span class=
              "command"><strong>untex</strong></span> or
              <span class="command"><strong>detex</strong></span>.
              Check <a class="ulink" href=
              "http://www.recoll.org/features.html#doctypes"
              target="_top">http://www.recoll.org/features.html</a>
              for sources if it's not packaged for your
              distribution.</p>
            </li>
            <li class="listitem">
              <p>dvi files need <span class=
              "command"><strong>dvips</strong></span>.</p>
            </li>
            <li class="listitem">
              <p>djvu files need <span class=
              "command"><strong>djvutxt</strong></span> and
              <span class="command"><strong>djvused</strong></span>
              from the <span class="application">DjVuLibre</span>
              package.</p>
            </li>
            <li class="listitem">
              <p>Audio files: <span class=
              "application">Recoll</span> releases 1.14 and later
              use a single <span class="application">Python</span>
              handler based on <span class=
              "application">mutagen</span> for all audio file
              types.</p>
            </li>
            <li class="listitem">
              <p>Pictures: <span class="application">Recoll</span>
              uses the <span class="application">Exiftool</span>
              <span class="application">Perl</span> package to
              extract tag information. Most image file formats are
              supported. Note that there may not be much interest
              in indexing the technical tags (image size, aperture,
              etc.). This is only of interest if you store personal
              tags or textual descriptions inside the image
              files.</p>
            </li>
            <li class="listitem">
              <p>chm: files in Microsoft help format need Python
              and the <span class="application">pychm</span> module
              (which needs <span class=
              "application">chmlib</span>).</p>
            </li>
            <li class="listitem">
              <p>ICS: up to <span class="application">Recoll</span>
              1.13, iCalendar files need <span class=
              "application">Python</span> and the <span class=
              "application">icalendar</span> module. <span class=
              "application">icalendar</span> is not needed for
              newer versions, which use internal code.</p>
            </li>
            <li class="listitem">
              <p>Zip archives need <span class=
              "application">Python</span> (and the standard zipfile
              module).</p>
            </li>
            <li class="listitem">
              <p>Rar archives need <span class=
              "application">Python</span>, the <span class=
              "application">rarfile</span> Python module and the
              <span class="command"><strong>unrar</strong></span>
              utility.</p>
            </li>
            <li class="listitem">
              <p>Midi karaoke files need <span class=
              "application">Python</span> and the <a class="ulink"
              href="http://pypi.python.org/pypi/midi/0.2.1" target=
              "_top"><span class="application">Midi
              module</span></a></p>
            </li>
            <li class="listitem">
              <p>Konqueror webarchive format with Python (uses the
              Tarfile module).</p>
            </li>
            <li class="listitem">
              <p>Mimehtml web archive format (support based on the
              email handler, which introduces some mild weirdness,
              but still usable).</p>
            </li>
          </ul>
        </div>
        <p>Text, HTML, email folders, and Scribus files are
        processed internally. <span class="application">Lyx</span>
        is used to index Lyx files. Many handlers need <span class=
        "command"><strong>iconv</strong></span> and the standard
        <span class="command"><strong>sed</strong></span> and
        <span class="command"><strong>awk</strong></span>.</p>
      </div>
      <div class="sect1">
        <div class="titlepage">
          <div>
            <div>
              <h2 class="title" style="clear: both"><a name=
              "RCL.INSTALL.BUILDING" id=
              "RCL.INSTALL.BUILDING"></a>6.3.&nbsp;Building from
              source</h2>
            </div>
          </div>
        </div>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name=
                "RCL.INSTALL.BUILDING.PREREQS" id=
                "RCL.INSTALL.BUILDING.PREREQS"></a>6.3.1.&nbsp;Prerequisites</h3>
              </div>
            </div>
          </div>
          <p>The following prerequisites are described in broad
          terms and not as specific package names (which will
          depend on the exact platform). The dependancies should be
          available as packages on most common Unix derivatives,
          and it should be quite uncommon that you would have to
          build one of them.</p>
          <p>The shopping list:</p>
          <div class="itemizedlist">
            <ul class="itemizedlist" style=
            "list-style-type: disc;">
              <li class="listitem">
                <p>The <span class=
                "command"><strong>autoconf</strong></span>,
                <span class=
                "command"><strong>automake</strong></span> and
                <span class=
                "command"><strong>libtool</strong></span> triad.
                Only <span class=
                "command"><strong>autoconf</strong></span> is
                needed for <span class="application">Recoll</span>
                1.21 and earlier.</p>
              </li>
              <li class="listitem">
                <p>C++ compiler. Recent versions require C++11
                compatibility (1.23 and later).</p>
              </li>
              <li class="listitem">
                <p><span class=
                "command"><strong>bison</strong></span> command
                (for <span class="application">Recoll</span> 1.21
                and later).</p>
              </li>
              <li class="listitem">
                <p><span class=
                "command"><strong>xsltproc</strong></span> command.
                For building the documentation (for <span class=
                "application">Recoll</span> 1.21 and later). This
                sometimes comes with the <span class=
                "application">libxslt</span> package. And also the
                Docbook XML and style sheet files.</p>
              </li>
              <li class="listitem">
                <p>Development files for <a class="ulink" href=
                "http://www.xapian.org" target="_top"><span class=
                "application">Xapian core</span></a>.</p>
                <div class="important" style=
                "margin-left: 0.5in; margin-right: 0.5in;">
                  <h3 class="title">Important</h3>
                  <p>If you are building Xapian for an older CPU
                  (before Pentium 4 or Athlon 64), you need to add
                  the <code class="option">--disable-sse</code>
                  flag to the configure command. Else all Xapian
                  application will crash with an <code class=
                  "literal">illegal instruction</code> error.</p>
                </div>
              </li>
              <li class="listitem">
                <p>Development files for <a class="ulink" href=
                "http://qt-project.org/downloads" target=
                "_top"><span class="application">Qt 4 or Qt
                5</span></a> . <span class=
                "application">Recoll</span> 1.15.9 was the last
                version to support <span class="application">Qt
                3</span>. If you do not want to install or build
                the <span class="application">Qt Webkit</span>
                module, <span class="application">Recoll</span> has
                a configuration option to disable its use (see
                further in the configuration section).</p>
              </li>
              <li class="listitem">
                <p>Development files for <span class=
                "application">X11</span> and <span class=
                "application">zlib</span>.</p>
              </li>
              <li class="listitem">
                <p>Development files for <span class=
                "application">Python</span> (or use <code class=
                "literal">--disable-python-module</code>).</p>
              </li>
              <li class="listitem">
                <p>You may also need <a class="ulink" href=
                "http://www.gnu.org/software/libiconv/" target=
                "_top">libiconv</a>. On <span class=
                "application">Linux</span> systems, the iconv
                interface is part of libc and you should not need
                to do anything special.</p>
              </li>
            </ul>
          </div>
          <p>Check the <a class="ulink" href=
          "http://www.recoll.org/download.html" target=
          "_top"><span class="application">Recoll</span> download
          page</a> for up to date version information.</p>
        </div>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name=
                "RCL.INSTALL.BUILDING.BUILDING" id=
                "RCL.INSTALL.BUILDING.BUILDING"></a>6.3.2.&nbsp;Building</h3>
              </div>
            </div>
          </div>
          <p><span class="application">Recoll</span> has been built
          on Linux, FreeBSD, Mac OS X, and Solaris, most versions
          after 2005 should be ok, maybe some older ones too
          (Solaris 8 is ok). If you build on another system, and
          need to modify things, <a class="ulink" href=
          "mailto:jfd@recoll.org" target="_top">I would very much
          welcome patches</a>.</p>
          <p><b>Configure options:&nbsp;</b></p>
          <div class="itemizedlist">
            <ul class="itemizedlist" style=
            "list-style-type: disc;">
              <li class="listitem">
                <p><code class="option">--without-aspell</code>
                will disable the code for phonetic matching of
                search terms.</p>
              </li>
              <li class="listitem">
                <p><code class="option">--with-fam</code> or
                <code class="option">--with-inotify</code> will
                enable the code for real time indexing. Inotify
                support is enabled by default on recent Linux
                systems.</p>
              </li>
              <li class="listitem">
                <p><code class="option">--with-qzeitgeist</code>
                will enable sending <span class=
                "application">Zeitgeist</span> events about the
                visited search results, and needs the <span class=
                "application">qzeitgeist</span> package.</p>
              </li>
              <li class="listitem">
                <p><code class="option">--disable-webkit</code> is
                available from version 1.17 to implement the result
                list with a <span class="application">Qt</span>
                QTextBrowser instead of a WebKit widget if you do
                not or can't depend on the latter.</p>
              </li>
              <li class="listitem">
                <p><code class="option">--disable-idxthreads</code>
                is available from version 1.19 to suppress
                multithreading inside the indexing process. You can
                also use the run-time configuration to restrict
                <span class=
                "command"><strong>recollindex</strong></span> to
                using a single thread, but the compile-time option
                may disable a few more unused locks. This only
                applies to the use of multithreading for the core
                index processing (data input). The <span class=
                "application">Recoll</span> monitor mode always
                uses at least two threads of execution.</p>
              </li>
              <li class="listitem">
                <p><code class=
                "option">--disable-python-module</code> will avoid
                building the <span class=
                "application">Python</span> module.</p>
              </li>
              <li class="listitem">
                <p><code class="option">--disable-xattr</code> will
                prevent fetching data from file extended
                attributes. Beyond a few standard attributes,
                fetching extended attributes data can only be
                useful is some application stores data in there,
                and also needs some simple configuration (see
                comments in the <code class=
                "filename">fields</code> configuration file).</p>
              </li>
              <li class="listitem">
                <p><code class="option">--enable-camelcase</code>
                will enable splitting <em class=
                "replaceable"><code>camelCase</code></em> words.
                This is not enabled by default as it has the
                unfortunate side-effect of making some phrase
                searches quite confusing: ie, <code class=
                "literal">"MySQL manual"</code> would be matched by
                <code class="literal">"MySQL manual"</code> and
                <code class="literal">"my sql manual"</code> but
                not <code class="literal">"mysql manual"</code>
                (only inside phrase searches).</p>
              </li>
              <li class="listitem">
                <p><code class="option">--with-file-command</code>
                Specify the version of the 'file' command to use
                (ie: --with-file-command=/usr/local/bin/file). Can
                be useful to enable the gnu version on systems
                where the native one is bad.</p>
              </li>
              <li class="listitem">
                <p><code class="option">--disable-qtgui</code>
                Disable the Qt interface. Will allow building the
                indexer and the command line search program in
                absence of a Qt environment.</p>
              </li>
              <li class="listitem">
                <p><code class="option">--disable-x11mon</code>
                Disable <span class="application">X11</span>
                connection monitoring inside recollindex. Together
                with --disable-qtgui, this allows building recoll
                without <span class="application">Qt</span> and
                <span class="application">X11</span>.</p>
              </li>
              <li class="listitem">
                <p><code class="option">--disable-userdoc</code>
                will avoid building the user manual. This avoids
                having to install the Docbook XML/XSL files and the
                TeX toolchain used for translating the manual to
                PDF.</p>
              </li>
              <li class="listitem">
                <p><code class="option">--disable-pic</code>
                (<span class="application">Recoll</span> versions
                up to 1.21 only) will compile <span class=
                "application">Recoll</span> with position-dependant
                code. This is incompatible with building the KIO or
                the <span class="application">Python</span> or
                <span class="application">PHP</span> extensions,
                but might yield very marginally faster code.</p>
              </li>
              <li class="listitem">
                <p>Of course the usual <span class=
                "application">autoconf</span> <span class=
                "command"><strong>configure</strong></span>
                options, like <code class="option">--prefix</code>
                apply.</p>
              </li>
            </ul>
          </div>
          <p>Normal procedure (for source extracted from a tar
          distribution):</p>
          <pre class="screen">
          <strong class=
"userinput"><code>cd recoll-xxx</code></strong>
          <strong class=
"userinput"><code>./configure</code></strong>
          <strong class="userinput"><code>make</code></strong>
          <strong class=
"userinput"><code>(practices usual hardship-repelling invocations)</code></strong>
        </pre>
          <p>When building from source cloned from the git
          repository, you also need to install <span class=
          "application">autoconf</span>, <span class=
          "application">automake</span>, and <span class=
          "application">libtool</span> and you must execute
          <code class="literal">sh autogen.sh</code> in the top
          source directory before running <code class=
          "literal">configure</code>.</p>
        </div>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name=
                "RCL.INSTALL.BUILDING.INSTALL" id=
                "RCL.INSTALL.BUILDING.INSTALL"></a>6.3.3.&nbsp;Installing</h3>
              </div>
            </div>
          </div>
          <p>Use <strong class="userinput"><code>make
          install</code></strong> in the root of the source tree.
          This will copy the commands to <code class=
          "filename"><em class=
          "replaceable"><code>prefix</code></em>/bin</code> and the
          sample configuration files, scripts and other shared data
          to <code class="filename"><em class=
          "replaceable"><code>prefix</code></em>/share/recoll</code>.</p>
        </div>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name=
                "RCL.INSTALL.BUILDING.PYTHON" id=
                "RCL.INSTALL.BUILDING.PYTHON"></a>6.3.4.&nbsp;Python
                API package</h3>
              </div>
            </div>
          </div>
          <p>The Python interface can be found in the source tree,
          under the <code class="filename">python/recoll</code>
          directory.</p>
          <p>As of <span class="application">Recoll</span> 1.19,
          the module can be compiled for Python3.</p>
          <p>The normal <span class="application">Recoll</span>
          build procedure (see above) installs the API package for
          the default system version (python) along with the main
          code. The package for other Python versions (e.g. python3
          if the system default is python2) must be explicitely
          built and installed.</p>
          <p>The <code class="filename">python/recoll/</code>
          directory contains the usual <code class=
          "filename">setup.py</code>. After configuring and
          building the main <span class="application">Recoll</span>
          code, you can use the script to build and install the
          Python module:</p>
          <pre class="screen">
          <strong class=
"userinput"><code>cd recoll-xxx/python/recoll</code></strong>
          <strong class=
"userinput"><code>pythonX setup.py build</code></strong>
          <strong class=
"userinput"><code>sudo pythonX setup.py install</code></strong>
        </pre>
        </div>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name=
                "RCL.INSTALL.BUILDING.SOLARIS" id=
                "RCL.INSTALL.BUILDING.SOLARIS"></a>6.3.5.&nbsp;Building
                on Solaris</h3>
              </div>
            </div>
          </div>
          <p>We did not test building the GUI on Solaris for recent
          versions. You will need at least Qt 4.4. There are some
          hints on <a class="ulink" href=
          "http://www.recoll.org/download-1.14.html" target=
          "_top">an old web site page</a>, they may still be
          valid.</p>
          <p>Someone did test the 1.19 indexer and Python module
          build, they do work, with a few minor glitches. Be sure
          to use GNU <span class=
          "command"><strong>make</strong></span> and <span class=
          "command"><strong>install</strong></span>.</p>
        </div>
      </div>
      <div class="sect1">
        <div class="titlepage">
          <div>
            <div>
              <h2 class="title" style="clear: both"><a name=
              "RCL.INSTALL.CONFIG" id=
              "RCL.INSTALL.CONFIG"></a>6.4.&nbsp;Configuration
              overview</h2>
            </div>
          </div>
        </div>
        <p>Most of the parameters specific to the <span class=
        "command"><strong>recoll</strong></span> GUI are set
        through the <span class="guilabel">Preferences</span> menu
        and stored in the standard Qt place (<code class=
        "filename">$HOME/.config/Recoll.org/recoll.conf</code>).
        You probably do not want to edit this by hand.</p>
        <p><span class="application">Recoll</span> indexing options
        are set inside text configuration files located in a
        configuration directory. There can be several such
        directories, each of which defines the parameters for one
        index.</p>
        <p>The configuration files can be edited by hand or through
        the <span class="guilabel">Index configuration</span>
        dialog (<span class="guilabel">Preferences</span> menu).
        The GUI tool will try to respect your formatting and
        comments as much as possible, so it is quite possible to
        use both approaches on the same configuration.</p>
        <p>The most accurate documentation for the configuration
        parameters is given by comments inside the default files,
        and we will just give a general overview here.</p>
        <p>For each index, there are at least two sets of
        configuration files. System-wide configuration files are
        kept in a directory named like <code class=
        "filename">/usr/share/recoll/examples</code>, and define
        default values, shared by all indexes. For each index, a
        parallel set of files defines the customized
        parameters.</p>
        <p>The default location of the customized configuration is
        the <code class="filename">.recoll</code> directory in your
        home. Most people will only use this directory.</p>
        <p>This location can be changed, or others can be added
        with the <code class="envar">RECOLL_CONFDIR</code>
        environment variable or the <code class="option">-c</code>
        option parameter to <span class=
        "command"><strong>recoll</strong></span> and <span class=
        "command"><strong>recollindex</strong></span>.</p>
        <p>In addition (as of <span class=
        "application">Recoll</span> version 1.19.7), it is possible
        to specify two additional configuration directories which
        will be stacked before and after the user configuration
        directory. These are defined by the <code class=
        "envar">RECOLL_CONFTOP</code> and <code class=
        "envar">RECOLL_CONFMID</code> environment variables. Values
        from configuration files inside the top directory will
        override user ones, values from configuration files inside
        the middle directory will override system ones and be
        overriden by user ones. These two variables may be of use
        to applications which augment <span class=
        "application">Recoll</span> functionality, and need to add
        configuration data without disturbing the user's files.
        Please note that the two, currently single, values will
        probably be interpreted as colon-separated lists in the
        future: do not use colon characters inside the directory
        paths.</p>
        <p>If the <code class="filename">.recoll</code> directory
        does not exist when <span class=
        "command"><strong>recoll</strong></span> or <span class=
        "command"><strong>recollindex</strong></span> are started,
        it will be created with a set of empty configuration files.
        <span class="command"><strong>recoll</strong></span> will
        give you a chance to edit the configuration file before
        starting indexing. <span class=
        "command"><strong>recollindex</strong></span> will proceed
        immediately. To avoid mistakes, the automatic directory
        creation will only occur for the default location, not if
        <code class="option">-c</code> or <code class=
        "envar">RECOLL_CONFDIR</code> were used (in the latter
        cases, you will have to create the directory).</p>
        <p>All configuration files share the same format. For
        example, a short extract of the main configuration file
        might look as follows:</p>
        <pre class="programlisting">
        # Space-separated list of files and directories to index.
        topdirs =  ~/docs /usr/share/doc

        [~/somedirectory-with-utf8-txt-files]
        defaultcharset = utf-8
      </pre>
        <p>There are three kinds of lines:</p>
        <div class="itemizedlist">
          <ul class="itemizedlist" style="list-style-type: disc;">
            <li class="listitem">
              <p>Comment (starts with <span class=
              "emphasis"><em>#</em></span>) or empty.</p>
            </li>
            <li class="listitem">
              <p>Parameter affectation (<span class=
              "emphasis"><em>name = value</em></span>).</p>
            </li>
            <li class="listitem">
              <p>Section definition ([<span class=
              "emphasis"><em>somedirname</em></span>]).</p>
            </li>
          </ul>
        </div>
        <p>Long lines can be broken by ending each incomplete part
        with a backslash (<code class="literal">\</code>).</p>
        <p>Depending on the type of configuration file, section
        definitions either separate groups of parameters or allow
        redefining some parameters for a directory sub-tree. They
        stay in effect until another section definition, or the end
        of file, is encountered. Some of the parameters used for
        indexing are looked up hierarchically from the current
        directory location upwards. Not all parameters can be
        meaningfully redefined, this is specified for each in the
        next section.</p>
        <div class="important" style=
        "margin-left: 0.5in; margin-right: 0.5in;">
          <h3 class="title">Important</h3>
          <p>Global parameters <span class="emphasis"><em>must
          not</em></span> be defined in a directory subsection,
          else they will not be found at all by the <span class=
          "application">Recoll</span> code, which looks for them at
          the top level (e.g. <code class=
          "literal">skippedPaths</code>).</p>
        </div>
        <p>When found at the beginning of a file path, the tilde
        character (~) is expanded to the name of the user's home
        directory, as a shell would do.</p>
        <p>Some parameters are lists of strings. White space is
        used for separation. List elements with embedded spaces can
        be quoted using double-quotes. Double quotes inside these
        elements can be escaped with a backslash.</p>
        <p>No value inside a configuration file can contain a
        newline character. Long lines can be continued by escaping
        the physical newline with backslash, even inside quoted
        strings.</p>
        <pre class="programlisting">
        astringlist =  "some string \
        with spaces"
        thesame = "some string with spaces"        
      </pre>
        <p>Parameters which are not part of string lists can't be
        quoted, and leading and trailing space characters are
        stripped before the value is used.</p>
        <p><b>Encoding issues.&nbsp;</b>Most of the configuration
        parameters are plain ASCII. Two particular sets of values
        may cause encoding issues:</p>
        <div class="itemizedlist">
          <ul class="itemizedlist" style="list-style-type: disc;">
            <li class="listitem">
              <p>File path parameters may contain non-ascii
              characters and should use the exact same byte values
              as found in the file system directory. Usually, this
              means that the configuration file should use the
              system default locale encoding.</p>
            </li>
            <li class="listitem">
              <p>The <code class="envar">unac_except_trans</code>
              parameter should be encoded in UTF-8. If your system
              locale is not UTF-8, and you need to also specify
              non-ascii file paths, this poses a difficulty because
              common text editors cannot handle multiple encodings
              in a single file. In this relatively unlikely case,
              you can edit the configuration file as two separate
              text files with appropriate encodings, and
              concatenate them to create the complete
              configuration.</p>
            </li>
          </ul>
        </div>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name=
                "RCL.INSTALL.CONFIG.ENVIR" id=
                "RCL.INSTALL.CONFIG.ENVIR"></a>6.4.1.&nbsp;Environment
                variables</h3>
              </div>
            </div>
          </div>
          <div class="variablelist">
            <dl class="variablelist">
              <dt><span class="term"><code class=
              "varname">RECOLL_CONFDIR</code></span></dt>
              <dd>
                <p>Defines the main configuration directory.</p>
              </dd>
              <dt><span class="term"><code class=
              "varname">RECOLL_TMPDIR, TMPDIR</code></span></dt>
              <dd>
                <p>Locations for temporary files, in this order of
                priority. The default if none of these is set is to
                use <code class="filename">/tmp</code>. Big
                temporary files may be created during indexing,
                mostly for decompressing, and also for processing,
                e.g. email attachments.</p>
              </dd>
              <dt><span class="term"><code class=
              "varname">RECOLL_CONFTOP,
              RECOLL_CONFMID</code></span></dt>
              <dd>
                <p>Allow adding configuration directories with
                priorities below and above the user directory (see
                above the Configuration overview section for
                details).</p>
              </dd>
              <dt><span class="term"><code class=
              "varname">RECOLL_EXTRA_DBS,
              RECOLL_ACTIVE_EXTRA_DBS</code></span></dt>
              <dd>
                <p>Help for setting up external indexes. See
                <a class="link" href="#RCL.SEARCH.GUI.MULTIDB"
                title="3.1.10.&nbsp;Multiple indexes">this
                paragraph</a> for explanations.</p>
              </dd>
              <dt><span class="term"><code class=
              "varname">RECOLL_DATADIR</code></span></dt>
              <dd>
                <p>Defines replacement for the default location of
                Recoll data files, normally found in, e.g.,
                <code class=
                "filename">/usr/share/recoll</code>).</p>
              </dd>
              <dt><span class="term"><code class=
              "varname">RECOLL_FILTERSDIR</code></span></dt>
              <dd>
                <p>Defines replacement for the default location of
                Recoll filters, normally found in, e.g.,
                <code class=
                "filename">/usr/share/recoll/filters</code>).</p>
              </dd>
              <dt><span class="term"><code class=
              "varname">ASPELL_PROG</code></span></dt>
              <dd>
                <p><span class=
                "command"><strong>aspell</strong></span> program to
                use for creating the spelling dictionary. The
                result has to be compatible with the <code class=
                "filename">libaspell</code> which <span class=
                "application">Recoll</span> is using.</p>
              </dd>
              <dt><span class="term"><code class=
              "varname">VARNAME</code></span></dt>
              <dd>
                <p>Blabla</p>
              </dd>
            </dl>
          </div>
        </div>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF" id=
                "RCL.INSTALL.CONFIG.RECOLLCONF"></a>6.4.2.&nbsp;Recoll
                main configuration file, recoll.conf</h3>
              </div>
            </div>
          </div>
          <div class="sect3">
            <div class="titlepage">
              <div>
                <div>
                  <h4 class="title"><a name=
                  "RCL.INSTALL.CONFIG.RECOLLCONF.WHATDOCS" id=
                  "RCL.INSTALL.CONFIG.RECOLLCONF.WHATDOCS"></a>6.4.2.1.&nbsp;Parameters
                  affecting what documents we index</h4>
                </div>
              </div>
            </div>
            <div class="variablelist">
              <dl class="variablelist">
                <dt><a name="RCL.INSTALL.CONFIG.RECOLLCONF.TOPDIRS"
                id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.TOPDIRS"></a><span class="term"><code class="varname">topdirs</code></span></dt>
                <dd>
                  <p>Space-separated list of files or directories
                  to recursively index. Default to ~ (indexes
                  $HOME). You can use symbolic links in the list,
                  they will be followed, independantly of the value
                  of the followLinks variable.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.MONITORDIRS" id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.MONITORDIRS"></a><span class="term"><code class="varname">monitordirs</code></span></dt>
                <dd>
                  <p>Space-separated list of files or directories
                  to monitor for updates. When running the
                  real-time indexer, this allows monitoring only a
                  subset of the whole indexed area. The elements
                  must be included in the tree defined by the
                  'topdirs' members.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.SKIPPEDNAMES" id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.SKIPPEDNAMES"></a><span class="term"><code class="varname">skippedNames</code></span></dt>
                <dd>
                  <p>Files and directories which should be ignored.
                  White space separated list of wildcard patterns
                  (simple ones, not paths, must contain no / ),
                  which will be tested against file and directory
                  names. The list in the default configuration does
                  not exclude hidden directories (names beginning
                  with a dot), which means that it may index quite
                  a few things that you do not want. On the other
                  hand, email user agents like Thunderbird usually
                  store messages in hidden directories, and you
                  probably want this indexed. One possible solution
                  is to have ".*" in "skippedNames", and add things
                  like "~/.thunderbird" "~/.evolution" to
                  "topdirs". Not even the file names are indexed
                  for patterns in this list, see the
                  "noContentSuffixes" variable for an alternative
                  approach which indexes the file names. Can be
                  redefined for any subtree.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.SKIPPEDNAMES-" id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.SKIPPEDNAMES-"></a><span class="term"><code class="varname">skippedNames-</code></span></dt>
                <dd>
                  <p>List of name endings to remove from the
                  default skippedNames list.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.SKIPPEDNAMES+" id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.SKIPPEDNAMES+"></a><span class="term"><code class="varname">skippedNames+</code></span></dt>
                <dd>
                  <p>List of name endings to add to the default
                  skippedNames list.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.NOCONTENTSUFFIXES"
                id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.NOCONTENTSUFFIXES"></a><span class="term"><code class="varname">noContentSuffixes</code></span></dt>
                <dd>
                  <p>List of name endings (not necessarily
                  dot-separated suffixes) for which we don't try
                  MIME type identification, and don't uncompress or
                  index content. Only the names will be indexed.
                  This complements the now obsoleted recoll_noindex
                  list from the mimemap file, which will go away in
                  a future release (the move from mimemap to
                  recoll.conf allows editing the list through the
                  GUI). This is different from skippedNames because
                  these are name ending matches only (not wildcard
                  patterns), and the file name itself gets indexed
                  normally. This can be redefined for
                  subdirectories.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.NOCONTENTSUFFIXES-"
                id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.NOCONTENTSUFFIXES-"></a><span class="term"><code class="varname">noContentSuffixes-</code></span></dt>
                <dd>
                  <p>List of name endings to remove from the
                  default noContentSuffixes list.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.NOCONTENTSUFFIXES+"
                id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.NOCONTENTSUFFIXES+"></a><span class="term"><code class="varname">noContentSuffixes+</code></span></dt>
                <dd>
                  <p>List of name endings to add to the default
                  noContentSuffixes list.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.SKIPPEDPATHS" id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.SKIPPEDPATHS"></a><span class="term"><code class="varname">skippedPaths</code></span></dt>
                <dd>
                  <p>Absolute paths we should not go into.
                  Space-separated list of wildcard expressions for
                  absolute filesystem paths. Must be defined at the
                  top level of the configuration file, not in a
                  subsection. Can contain files and directories.
                  The database and configuration directories will
                  automatically be added. The expressions are
                  matched using 'fnmatch(3)' with the FNM_PATHNAME
                  flag set by default. This means that '/'
                  characters must be matched explicitely. You can
                  set 'skippedPathsFnmPathname' to 0 to disable the
                  use of FNM_PATHNAME (meaning that '/*/dir3' will
                  match '/dir1/dir2/dir3'). The default value
                  contains the usual mount point for removable
                  media to remind you that it is a bad idea to have
                  Recoll work on these (esp. with the monitor:
                  media gets indexed on mount, all data gets erased
                  on unmount). Explicitely adding '/media/xxx' to
                  the 'topdirs' variable will override this.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.SKIPPEDPATHSFNMPATHNAME"
                id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.SKIPPEDPATHSFNMPATHNAME">
                </a><span class="term"><code class=
                "varname">skippedPathsFnmPathname</code></span></dt>
                <dd>
                  <p>Set to 0 to override use of FNM_PATHNAME for
                  matching skipped paths.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.NOWALKFN" id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.NOWALKFN"></a><span class="term"><code class="varname">nowalkfn</code></span></dt>
                <dd>
                  <p>File name which will cause its parent
                  directory to be skipped. Any directory containing
                  a file with this name will be skipped as if it
                  was part of the skippedPaths list. Ex:
                  .recoll-noindex</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.DAEMSKIPPEDPATHS"
                id="RCL.INSTALL.CONFIG.RECOLLCONF.DAEMSKIPPEDPATHS">
                </a><span class="term"><code class=
                "varname">daemSkippedPaths</code></span></dt>
                <dd>
                  <p>skippedPaths equivalent specific to real time
                  indexing. This enables having parts of the tree
                  which are initially indexed but not monitored. If
                  daemSkippedPaths is not set, the daemon uses
                  skippedPaths.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.ZIPUSESKIPPEDNAMES"
                id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.ZIPUSESKIPPEDNAMES"></a><span class="term"><code class="varname">zipUseSkippedNames</code></span></dt>
                <dd>
                  <p>Use skippedNames inside Zip archives. Fetched
                  directly by the rclzip handler. Skip the patterns
                  defined by skippedNames inside Zip archives. Can
                  be redefined for subdirectories. See
                  https://www.lesbonscomptes.com/recoll/faqsandhowtos/FilteringOutZipArchiveMembers.html</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.ZIPSKIPPEDNAMES" id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.ZIPSKIPPEDNAMES"></a><span class="term"><code class="varname">zipSkippedNames</code></span></dt>
                <dd>
                  <p>Space-separated list of wildcard expressions
                  for names that should be ignored inside zip
                  archives. This is used directly by the zip
                  handler. If zipUseSkippedNames is not set,
                  zipSkippedNames defines the patterns to be
                  skipped inside archives. If zipUseSkippedNames is
                  set, the two lists are concatenated and used. Can
                  be redefined for subdirectories. See
                  https://www.lesbonscomptes.com/recoll/faqsandhowtos/FilteringOutZipArchiveMembers.html</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.FOLLOWLINKS" id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.FOLLOWLINKS"></a><span class="term"><code class="varname">followLinks</code></span></dt>
                <dd>
                  <p>Follow symbolic links during indexing. The
                  default is to ignore symbolic links to avoid
                  multiple indexing of linked files. No effort is
                  made to avoid duplication when this option is set
                  to true. This option can be set individually for
                  each of the 'topdirs' members by using sections.
                  It can not be changed below the 'topdirs' level.
                  Links in the 'topdirs' list itself are always
                  followed.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.INDEXEDMIMETYPES"
                id="RCL.INSTALL.CONFIG.RECOLLCONF.INDEXEDMIMETYPES">
                </a><span class="term"><code class=
                "varname">indexedmimetypes</code></span></dt>
                <dd>
                  <p>Restrictive list of indexed mime types.
                  Normally not set (in which case all supported
                  types are indexed). If it is set, only the types
                  from the list will have their contents indexed.
                  The names will be indexed anyway if
                  indexallfilenames is set (default). MIME type
                  names should be taken from the mimemap file (the
                  values may be different from xdg-mime or file -i
                  output in some cases). Can be redefined for
                  subtrees.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.EXCLUDEDMIMETYPES"
                id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.EXCLUDEDMIMETYPES"></a><span class="term"><code class="varname">excludedmimetypes</code></span></dt>
                <dd>
                  <p>List of excluded MIME types. Lets you exclude
                  some types from indexing. MIME type names should
                  be taken from the mimemap file (the values may be
                  different from xdg-mime or file -i output in some
                  cases) Can be redefined for subtrees.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.NOMD5TYPES" id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.NOMD5TYPES"></a><span class="term"><code class="varname">nomd5types</code></span></dt>
                <dd>
                  <p>Don't compute md5 for these types. md5
                  checksums are used only for deduplicating
                  results, and can be very expensive to compute on
                  multimedia or other big files. This list lets you
                  turn off md5 computation for selected types. It
                  is global (no redefinition for subtrees). At the
                  moment, it only has an effect for external
                  handlers (exec and execm). The file types can be
                  specified by listing either MIME types (e.g.
                  audio/mpeg) or handler names (e.g. rclaudio).</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.COMPRESSEDFILEMAXKBS"
                id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.COMPRESSEDFILEMAXKBS">
                </a><span class="term"><code class=
                "varname">compressedfilemaxkbs</code></span></dt>
                <dd>
                  <p>Size limit for compressed files. We need to
                  decompress these in a temporary directory for
                  identification, which can be wasteful in some
                  cases. Limit the waste. Negative means no limit.
                  0 results in no processing of any compressed
                  file. Default 50 MB.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.TEXTFILEMAXMBS" id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.TEXTFILEMAXMBS"></a><span class="term"><code class="varname">textfilemaxmbs</code></span></dt>
                <dd>
                  <p>Size limit for text files. Mostly for skipping
                  monster logs. Default 20 MB.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.INDEXALLFILENAMES"
                id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.INDEXALLFILENAMES"></a><span class="term"><code class="varname">indexallfilenames</code></span></dt>
                <dd>
                  <p>Index the file names of unprocessed files
                  Index the names of files the contents of which we
                  don't index because of an excluded or unsupported
                  MIME type.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.USESYSTEMFILECOMMAND"
                id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.USESYSTEMFILECOMMAND">
                </a><span class="term"><code class=
                "varname">usesystemfilecommand</code></span></dt>
                <dd>
                  <p>Use a system command for file MIME type
                  guessing as a final step in file type
                  identification This is generally useful, but will
                  usually cause the indexing of many bogus 'text'
                  files. See 'systemfilecommand' for the command
                  used.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.SYSTEMFILECOMMAND"
                id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.SYSTEMFILECOMMAND"></a><span class="term"><code class="varname">systemfilecommand</code></span></dt>
                <dd>
                  <p>Command used to guess MIME types if the
                  internal methods fails This should be a "file -i"
                  workalike. The file path will be added as a last
                  parameter to the command line. 'xdg-mime' works
                  better than the traditional 'file' command, and
                  is now the configured default (with a hard-coded
                  fallback to 'file')</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.PROCESSWEBQUEUE" id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.PROCESSWEBQUEUE"></a><span class="term"><code class="varname">processwebqueue</code></span></dt>
                <dd>
                  <p>Decide if we process the Web queue. The queue
                  is a directory where the Recoll Web browser
                  plugins create the copies of visited pages.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.TEXTFILEPAGEKBS" id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.TEXTFILEPAGEKBS"></a><span class="term"><code class="varname">textfilepagekbs</code></span></dt>
                <dd>
                  <p>Page size for text files. If this is set,
                  text/plain files will be divided into documents
                  of approximately this size. Will reduce memory
                  usage at index time and help with loading data in
                  the preview window at query time. Particularly
                  useful with very big files, such as application
                  or system logs. Also see textfilemaxmbs and
                  compressedfilemaxkbs.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.MEMBERMAXKBS" id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.MEMBERMAXKBS"></a><span class="term"><code class="varname">membermaxkbs</code></span></dt>
                <dd>
                  <p>Size limit for archive members. This is passed
                  to the filters in the environment as
                  RECOLL_FILTER_MAXMEMBERKB.</p>
                </dd>
              </dl>
            </div>
          </div>
          <div class="sect3">
            <div class="titlepage">
              <div>
                <div>
                  <h4 class="title"><a name=
                  "RCL.INSTALL.CONFIG.RECOLLCONF.TERMS" id=
                  "RCL.INSTALL.CONFIG.RECOLLCONF.TERMS"></a>6.4.2.2.&nbsp;Parameters
                  affecting how we generate terms and organize the
                  index</h4>
                </div>
              </div>
            </div>
            <div class="variablelist">
              <dl class="variablelist">
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.INDEXSTRIPCHARS" id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.INDEXSTRIPCHARS"></a><span class="term"><code class="varname">indexStripChars</code></span></dt>
                <dd>
                  <p>Decide if we store character case and
                  diacritics in the index. If we do, searches
                  sensitive to case and diacritics can be
                  performed, but the index will be bigger, and some
                  marginal weirdness may sometimes occur. The
                  default is a stripped index. When using multiple
                  indexes for a search, this parameter must be
                  defined identically for all. Changing the value
                  implies an index reset.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.INDEXSTOREDOCTEXT"
                id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.INDEXSTOREDOCTEXT"></a><span class="term"><code class="varname">indexStoreDocText</code></span></dt>
                <dd>
                  <p>Decide if we store the documents' text content
                  in the index. Storing the text allows extracting
                  snippets from it at query time, instead of
                  building them from index position data. Newer
                  Xapian index formats have rendered our use of
                  positions list unacceptably slow in some cases.
                  The last Xapian index format with good
                  performance for the old method is Chert, which is
                  default for 1.2, still supported but not default
                  in 1.4 and will be dropped in 1.6. The stored
                  document text is translated from its original
                  format to UTF-8 plain text, but not stripped of
                  upper-case, diacritics, or punctuation signs.
                  Storing it increases the index size by 10-20%
                  typically, but also allows for nicer snippets, so
                  it may be worth enabling it even if not strictly
                  needed for performance if you can afford the
                  space. The variable only has an effect when
                  creating an index, meaning that the xapiandb
                  directory must not exist yet. Its exact effect
                  depends on the Xapian version. For Xapian 1.4, if
                  the variable is set to 0, the Chert format will
                  be used, and the text will not be stored. If the
                  variable is 1, Glass will be used, and the text
                  stored. For Xapian 1.2, and for versions after
                  1.5 and newer, the index format is always the
                  default, but the variable controls if the text is
                  stored or not, and the abstract generation
                  method. With Xapian 1.5 and later, and the
                  variable set to 0, abstract generation may be
                  very slow, but this setting may still be useful
                  to save space if you do not use abstract
                  generation at all.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.NONUMBERS" id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.NONUMBERS"></a><span class="term"><code class="varname">nonumbers</code></span></dt>
                <dd>
                  <p>Decides if terms will be generated for
                  numbers. For example "123", "1.5e6", 192.168.1.4,
                  would not be indexed if nonumbers is set
                  ("value123" would still be). Numbers are often
                  quite interesting to search for, and this should
                  probably not be set except for special
                  situations, ie, scientific documents with huge
                  amounts of numbers in them, where setting
                  nonumbers will reduce the index size. This can
                  only be set for a whole index, not for a
                  subtree.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.DEHYPHENATE" id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.DEHYPHENATE"></a><span class="term"><code class="varname">dehyphenate</code></span></dt>
                <dd>
                  <p>Determines if we index 'coworker' also when
                  the input is 'co-worker'. This is new in version
                  1.22, and on by default. Setting the variable to
                  off allows restoring the previous behaviour.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.BACKSLASHASLETTER"
                id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.BACKSLASHASLETTER"></a><span class="term"><code class="varname">backslashasletter</code></span></dt>
                <dd>
                  <p>Process backslash as normal letter This may
                  make sense for people wanting to index TeX
                  commands as such but is not of much general
                  use.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.MAXTERMLENGTH" id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.MAXTERMLENGTH"></a><span class="term"><code class="varname">maxtermlength</code></span></dt>
                <dd>
                  <p>Maximum term length. Words longer than this
                  will be discarded. The default is 40 and used to
                  be hard-coded, but it can now be adjusted. You
                  need an index reset if you change the value.</p>
                </dd>
                <dt><a name="RCL.INSTALL.CONFIG.RECOLLCONF.NOCJK"
                id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.NOCJK"></a><span class="term"><code class="varname">nocjk</code></span></dt>
                <dd>
                  <p>Decides if specific East Asian (Chinese Korean
                  Japanese) characters/word splitting is turned
                  off. This will save a small amount of CPU if you
                  have no CJK documents. If your document base does
                  include such text but you are not interested in
                  searching it, setting nocjk may be a significant
                  time and space saver.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.CJKNGRAMLEN" id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.CJKNGRAMLEN"></a><span class="term"><code class="varname">cjkngramlen</code></span></dt>
                <dd>
                  <p>This lets you adjust the size of n-grams used
                  for indexing CJK text. The default value of 2 is
                  probably appropriate in most cases. A value of 3
                  would allow more precision and efficiency on
                  longer words, but the index will be approximately
                  twice as large.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.INDEXSTEMMINGLANGUAGES"
                id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.INDEXSTEMMINGLANGUAGES">
                </a><span class="term"><code class=
                "varname">indexstemminglanguages</code></span></dt>
                <dd>
                  <p>Languages for which to create stemming
                  expansion data. Stemmer names can be found by
                  executing 'recollindex -l', or this can also be
                  set from a list in the GUI.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.DEFAULTCHARSET" id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.DEFAULTCHARSET"></a><span class="term"><code class="varname">defaultcharset</code></span></dt>
                <dd>
                  <p>Default character set. This is used for files
                  which do not contain a character set definition
                  (e.g.: text/plain). Values found inside files,
                  e.g. a 'charset' tag in HTML documents, will
                  override it. If this is not set, the default
                  character set is the one defined by the NLS
                  environment ($LC_ALL, $LC_CTYPE, $LANG), or
                  ultimately iso-8859-1 (cp-1252 in fact). If for
                  some reason you want a general default which does
                  not match your LANG and is not 8859-1, use this
                  variable. This can be redefined for any
                  sub-directory.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.UNAC_EXCEPT_TRANS"
                id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.UNAC_EXCEPT_TRANS"></a><span class="term"><code class="varname">unac_except_trans</code></span></dt>
                <dd>
                  <p>A list of characters, encoded in UTF-8, which
                  should be handled specially when converting text
                  to unaccented lowercase. For example, in Swedish,
                  the letter a with diaeresis has full alphabet
                  citizenship and should not be turned into an a.
                  Each element in the space-separated list has the
                  special character as first element and the
                  translation following. The handling of both the
                  lowercase and upper-case versions of a character
                  should be specified, as appartenance to the list
                  will turn-off both standard accent and case
                  processing. The value is global and affects both
                  indexing and querying. Examples: Swedish:
                  unac_except_trans = ää Ää öö Öö üü Üü ßss œoe Œoe
                  æae Æae ﬀff ﬁfi ﬂfl åå Åå . German:
                  unac_except_trans = ää Ää öö Öö üü Üü ßss œoe Œoe
                  æae Æae ﬀff ﬁfi ﬂfl In French, you probably want
                  to decompose oe and ae and nobody would type a
                  German ß unac_except_trans = ßss œoe Œoe æae Æae
                  ﬀff ﬁfi ﬂfl . The default for all until someone
                  protests follows. These decompositions are not
                  performed by unac, but it is unlikely that
                  someone would type the composed forms in a
                  search. unac_except_trans = ßss œoe Œoe æae Æae
                  ﬀff ﬁfi ﬂfl</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.MAILDEFCHARSET" id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.MAILDEFCHARSET"></a><span class="term"><code class="varname">maildefcharset</code></span></dt>
                <dd>
                  <p>Overrides the default character set for email
                  messages which don't specify one. This is mainly
                  useful for readpst (libpst) dumps, which are
                  utf-8 but do not say so.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.LOCALFIELDS" id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.LOCALFIELDS"></a><span class="term"><code class="varname">localfields</code></span></dt>
                <dd>
                  <p>Set fields on all files (usually of a specific
                  fs area). Syntax is the usual: name = value ;
                  attr1 = val1 ; [...] value is empty so this needs
                  an initial semi-colon. This is useful, e.g., for
                  setting the rclaptg field for application
                  selection inside mimeview.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.TESTMODIFUSEMTIME"
                id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.TESTMODIFUSEMTIME"></a><span class="term"><code class="varname">testmodifusemtime</code></span></dt>
                <dd>
                  <p>Use mtime instead of ctime to test if a file
                  has been modified. The time is used in addition
                  to the size, which is always used. Setting this
                  can reduce re-indexing on systems where extended
                  attributes are used (by some other application),
                  but not indexed, because changing extended
                  attributes only affects ctime. Notes: - This may
                  prevent detection of change in some marginal file
                  rename cases (the target would need to have the
                  same size and mtime). - You should probably also
                  set noxattrfields to 1 in this case, except if
                  you still prefer to perform xattr indexing, for
                  example if the local file update pattern makes it
                  of value (as in general, there is a risk for pure
                  extended attributes updates without file
                  modification to go undetected). Perform a full
                  index reset after changing this.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.NOXATTRFIELDS" id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.NOXATTRFIELDS"></a><span class="term"><code class="varname">noxattrfields</code></span></dt>
                <dd>
                  <p>Disable extended attributes conversion to
                  metadata fields. This probably needs to be set if
                  testmodifusemtime is set.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.METADATACMDS" id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.METADATACMDS"></a><span class="term"><code class="varname">metadatacmds</code></span></dt>
                <dd>
                  <p>Define commands to gather external metadata,
                  e.g. tmsu tags. There can be several entries,
                  separated by semi-colons, each defining which
                  field name the data goes into and the command to
                  use. Don't forget the initial semi-colon. All the
                  field names must be different. You can use
                  aliases in the "field" file if necessary. As a
                  not too pretty hack conceded to convenience, any
                  field name beginning with "rclmulti" will be
                  taken as an indication that the command returns
                  multiple field values inside a text blob
                  formatted as a recoll configuration file
                  ("fieldname = fieldvalue" lines). The rclmultixx
                  name will be ignored, and field names and values
                  will be parsed from the data. Example:
                  metadatacmds = ; tags = tmsu tags %f; rclmulti1 =
                  cmdOutputsConf %f</p>
                </dd>
              </dl>
            </div>
          </div>
          <div class="sect3">
            <div class="titlepage">
              <div>
                <div>
                  <h4 class="title"><a name=
                  "RCL.INSTALL.CONFIG.RECOLLCONF.STORE" id=
                  "RCL.INSTALL.CONFIG.RECOLLCONF.STORE"></a>6.4.2.3.&nbsp;Parameters
                  affecting where and how we store things</h4>
                </div>
              </div>
            </div>
            <div class="variablelist">
              <dl class="variablelist">
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.CACHEDIR" id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.CACHEDIR"></a><span class="term"><code class="varname">cachedir</code></span></dt>
                <dd>
                  <p>Top directory for Recoll data. Recoll data
                  directories are normally located relative to the
                  configuration directory (e.g. ~/.recoll/xapiandb,
                  ~/.recoll/mboxcache). If 'cachedir' is set, the
                  directories are stored under the specified value
                  instead (e.g. if cachedir is ~/.cache/recoll, the
                  default dbdir would be ~/.cache/recoll/xapiandb).
                  This affects dbdir, webcachedir, mboxcachedir,
                  aspellDicDir, which can still be individually
                  specified to override cachedir. Note that if you
                  have multiple configurations, each must have a
                  different cachedir, there is no automatic
                  computation of a subpath under cachedir.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.MAXFSOCCUPPC" id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.MAXFSOCCUPPC"></a><span class="term"><code class="varname">maxfsoccuppc</code></span></dt>
                <dd>
                  <p>Maximum file system occupation over which we
                  stop indexing. The value is a percentage,
                  corresponding to what the "Capacity" df output
                  column shows. The default value is 0, meaning no
                  checking.</p>
                </dd>
                <dt><a name="RCL.INSTALL.CONFIG.RECOLLCONF.DBDIR"
                id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.DBDIR"></a><span class="term"><code class="varname">dbdir</code></span></dt>
                <dd>
                  <p>Xapian database directory location. This will
                  be created on first indexing. If the value is not
                  an absolute path, it will be interpreted as
                  relative to cachedir if set, or the configuration
                  directory (-c argument or $RECOLL_CONFDIR). If
                  nothing is specified, the default is then
                  ~/.recoll/xapiandb/</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.IDXSTATUSFILE" id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.IDXSTATUSFILE"></a><span class="term"><code class="varname">idxstatusfile</code></span></dt>
                <dd>
                  <p>Name of the scratch file where the indexer
                  process updates its status. Default:
                  idxstatus.txt inside the configuration
                  directory.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.MBOXCACHEDIR" id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.MBOXCACHEDIR"></a><span class="term"><code class="varname">mboxcachedir</code></span></dt>
                <dd>
                  <p>Directory location for storing mbox message
                  offsets cache files. This is normally 'mboxcache'
                  under cachedir if set, or else under the
                  configuration directory, but it may be useful to
                  share a directory between different
                  configurations.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.MBOXCACHEMINMBS" id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.MBOXCACHEMINMBS"></a><span class="term"><code class="varname">mboxcacheminmbs</code></span></dt>
                <dd>
                  <p>Minimum mbox file size over which we cache the
                  offsets. There is really no sense in caching
                  offsets for small files. The default is 5 MB.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.WEBCACHEDIR" id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.WEBCACHEDIR"></a><span class="term"><code class="varname">webcachedir</code></span></dt>
                <dd>
                  <p>Directory where we store the archived web
                  pages. This is only used by the web history
                  indexing code Default: cachedir/webcache if
                  cachedir is set, else
                  $RECOLL_CONFDIR/webcache</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.WEBCACHEMAXMBS" id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.WEBCACHEMAXMBS"></a><span class="term"><code class="varname">webcachemaxmbs</code></span></dt>
                <dd>
                  <p>Maximum size in MB of the Web archive. This is
                  only used by the web history indexing code.
                  Default: 40 MB. Reducing the size will not
                  physically truncate the file.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.WEBQUEUEDIR" id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.WEBQUEUEDIR"></a><span class="term"><code class="varname">webqueuedir</code></span></dt>
                <dd>
                  <p>The path to the Web indexing queue. This used
                  to be hard-coded in the old plugin as
                  ~/.recollweb/ToIndex so there would be no need or
                  possibility to change it, but the WebExtensions
                  plugin now downloads the files to the user
                  Downloads directory, and a script moves them to
                  webqueuedir. The script reads this value from the
                  config so it has become possible to change
                  it.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.WEBDOWNLOADSDIR" id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.WEBDOWNLOADSDIR"></a><span class="term"><code class="varname">webdownloadsdir</code></span></dt>
                <dd>
                  <p>The path to browser downloads directory. This
                  is where the new browser add-on extension has to
                  create the files. They are then moved by a script
                  to webqueuedir.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.ASPELLDICDIR" id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.ASPELLDICDIR"></a><span class="term"><code class="varname">aspellDicDir</code></span></dt>
                <dd>
                  <p>Aspell dictionary storage directory location.
                  The aspell dictionary (aspdict.(lang).rws) is
                  normally stored in the directory specified by
                  cachedir if set, or under the configuration
                  directory.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.FILTERSDIR" id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.FILTERSDIR"></a><span class="term"><code class="varname">filtersdir</code></span></dt>
                <dd>
                  <p>Directory location for executable input
                  handlers. If RECOLL_FILTERSDIR is set in the
                  environment, we use it instead. Defaults to
                  $prefix/share/recoll/filters. Can be redefined
                  for subdirectories.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.ICONSDIR" id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.ICONSDIR"></a><span class="term"><code class="varname">iconsdir</code></span></dt>
                <dd>
                  <p>Directory location for icons. The only reason
                  to change this would be if you want to change the
                  icons displayed in the result list. Defaults to
                  $prefix/share/recoll/images</p>
                </dd>
              </dl>
            </div>
          </div>
          <div class="sect3">
            <div class="titlepage">
              <div>
                <div>
                  <h4 class="title"><a name=
                  "RCL.INSTALL.CONFIG.RECOLLCONF.PERFS" id=
                  "RCL.INSTALL.CONFIG.RECOLLCONF.PERFS"></a>6.4.2.4.&nbsp;Parameters
                  affecting indexing performance and resource
                  usage</h4>
                </div>
              </div>
            </div>
            <div class="variablelist">
              <dl class="variablelist">
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.IDXFLUSHMB" id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.IDXFLUSHMB"></a><span class="term"><code class="varname">idxflushmb</code></span></dt>
                <dd>
                  <p>Threshold (megabytes of new data) where we
                  flush from memory to disk index. Setting this
                  allows some control over memory usage by the
                  indexer process. A value of 0 means no explicit
                  flushing, which lets Xapian perform its own
                  thing, meaning flushing every
                  $XAPIAN_FLUSH_THRESHOLD documents created,
                  modified or deleted: as memory usage depends on
                  average document size, not only document count,
                  the Xapian approach is is not very useful, and
                  you should let Recoll manage the flushes. The
                  program compiled value is 0. The configured
                  default value (from this file) is now 50 MB, and
                  should be ok in many cases. You can set it as low
                  as 10 to conserve memory, but if you are looking
                  for maximum speed, you may want to experiment
                  with values between 20 and 200. In my experience,
                  values beyond this are always counterproductive.
                  If you find otherwise, please drop me a note.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.FILTERMAXSECONDS"
                id="RCL.INSTALL.CONFIG.RECOLLCONF.FILTERMAXSECONDS">
                </a><span class="term"><code class=
                "varname">filtermaxseconds</code></span></dt>
                <dd>
                  <p>Maximum external filter execution time in
                  seconds. Default 1200 (20mn). Set to 0 for no
                  limit. This is mainly to avoid infinite loops in
                  postscript files (loop.ps)</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.FILTERMAXMBYTES" id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.FILTERMAXMBYTES"></a><span class="term"><code class="varname">filtermaxmbytes</code></span></dt>
                <dd>
                  <p>Maximum virtual memory space for filter
                  processes (setrlimit(RLIMIT_AS)), in megabytes.
                  Note that this includes any mapped libs (there is
                  no reliable Linux way to limit the data space
                  only), so we need to be a bit generous here.
                  Anything over 2000 will be ignored on 32 bits
                  machines.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.THRQSIZES" id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.THRQSIZES"></a><span class="term"><code class="varname">thrQSizes</code></span></dt>
                <dd>
                  <p>Stage input queues configuration. There are
                  three internal queues in the indexing pipeline
                  stages (file data extraction, terms generation,
                  index update). This parameter defines the queue
                  depths for each stage (three integer values). If
                  a value of -1 is given for a given stage, no
                  queue is used, and the thread will go on
                  performing the next stage. In practise, deep
                  queues have not been shown to increase
                  performance. Default: a value of 0 for the first
                  queue tells Recoll to perform autoconfiguration
                  based on the detected number of CPUs (no need for
                  the two other values in this case). Use thrQSizes
                  = -1 -1 -1 to disable multithreading
                  entirely.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.THRTCOUNTS" id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.THRTCOUNTS"></a><span class="term"><code class="varname">thrTCounts</code></span></dt>
                <dd>
                  <p>Number of threads used for each indexing
                  stage. The three stages are: file data
                  extraction, terms generation, index update). The
                  use of the counts is also controlled by some
                  special values in thrQSizes: if the first queue
                  depth is 0, all counts are ignored
                  (autoconfigured); if a value of -1 is used for a
                  queue depth, the corresponding thread count is
                  ignored. It makes no sense to use a value other
                  than 1 for the last stage because updating the
                  Xapian index is necessarily single-threaded (and
                  protected by a mutex).</p>
                </dd>
              </dl>
            </div>
          </div>
          <div class="sect3">
            <div class="titlepage">
              <div>
                <div>
                  <h4 class="title"><a name=
                  "RCL.INSTALL.CONFIG.RECOLLCONF.MISC" id=
                  "RCL.INSTALL.CONFIG.RECOLLCONF.MISC"></a>6.4.2.5.&nbsp;Miscellaneous
                  parameters</h4>
                </div>
              </div>
            </div>
            <div class="variablelist">
              <dl class="variablelist">
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.LOGLEVEL" id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.LOGLEVEL"></a><span class="term"><code class="varname">loglevel</code></span></dt>
                <dd>
                  <p>Log file verbosity 1-6. A value of 2 will
                  print only errors and warnings. 3 will print
                  information like document updates, 4 is quite
                  verbose and 6 very verbose.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.LOGFILENAME" id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.LOGFILENAME"></a><span class="term"><code class="varname">logfilename</code></span></dt>
                <dd>
                  <p>Log file destination. Use 'stderr' (default)
                  to write to the console.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.IDXLOGLEVEL" id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.IDXLOGLEVEL"></a><span class="term"><code class="varname">idxloglevel</code></span></dt>
                <dd>
                  <p>Override loglevel for the indexer.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.IDXLOGFILENAME" id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.IDXLOGFILENAME"></a><span class="term"><code class="varname">idxlogfilename</code></span></dt>
                <dd>
                  <p>Override logfilename for the indexer.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.DAEMLOGLEVEL" id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.DAEMLOGLEVEL"></a><span class="term"><code class="varname">daemloglevel</code></span></dt>
                <dd>
                  <p>Override loglevel for the indexer in real time
                  mode. The default is to use the idx... values if
                  set, else the log... values.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.DAEMLOGFILENAME" id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.DAEMLOGFILENAME"></a><span class="term"><code class="varname">daemlogfilename</code></span></dt>
                <dd>
                  <p>Override logfilename for the indexer in real
                  time mode. The default is to use the idx...
                  values if set, else the log... values.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.ORGIDXCONFDIR" id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.ORGIDXCONFDIR"></a><span class="term"><code class="varname">orgidxconfdir</code></span></dt>
                <dd>
                  <p>Original location of the configuration
                  directory. This is used exclusively for movable
                  datasets. Locating the configuration directory
                  inside the directory tree makes it possible to
                  provide automatic query time path translations
                  once the data set has moved (for example, because
                  it has been mounted on another location).</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.CURIDXCONFDIR" id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.CURIDXCONFDIR"></a><span class="term"><code class="varname">curidxconfdir</code></span></dt>
                <dd>
                  <p>Current location of the configuration
                  directory. Complement orgidxconfdir for movable
                  datasets. This should be used if the
                  configuration directory has been copied from the
                  dataset to another location, either because the
                  dataset is readonly and an r/w copy is desired,
                  or for performance reasons. This records the
                  original moved location before copy, to allow
                  path translation computations. For example if a
                  dataset originally indexed as
                  '/home/me/mydata/config' has been mounted to
                  '/media/me/mydata', and the GUI is running from a
                  copied configuration, orgidxconfdir would be
                  '/home/me/mydata/config', and curidxconfdir (as
                  set in the copied configuration) would be
                  '/media/me/mydata/config'.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.IDXRUNDIR" id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.IDXRUNDIR"></a><span class="term"><code class="varname">idxrundir</code></span></dt>
                <dd>
                  <p>Indexing process current directory. The input
                  handlers sometimes leave temporary files in the
                  current directory, so it makes sense to have
                  recollindex chdir to some temporary directory. If
                  the value is empty, the current directory is not
                  changed. If the value is (literal) tmp, we use
                  the temporary directory as set by the environment
                  (RECOLL_TMPDIR else TMPDIR else /tmp). If the
                  value is an absolute path to a directory, we go
                  there.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.CHECKNEEDRETRYINDEXSCRIPT"
                id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.CHECKNEEDRETRYINDEXSCRIPT">
                </a><span class="term"><code class=
                "varname">checkneedretryindexscript</code></span></dt>
                <dd>
                  <p>Script used to heuristically check if we need
                  to retry indexing files which previously failed.
                  The default script checks the modified dates on
                  /usr/bin and /usr/local/bin. A relative path will
                  be looked up in the filters dirs, then in the
                  path. Use an absolute path to do otherwise.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.RECOLLHELPERPATH"
                id="RCL.INSTALL.CONFIG.RECOLLCONF.RECOLLHELPERPATH">
                </a><span class="term"><code class=
                "varname">recollhelperpath</code></span></dt>
                <dd>
                  <p>Additional places to search for helper
                  executables. This is only used on Windows for
                  now.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.IDXABSMLEN" id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.IDXABSMLEN"></a><span class="term"><code class="varname">idxabsmlen</code></span></dt>
                <dd>
                  <p>Length of abstracts we store while indexing.
                  Recoll stores an abstract for each indexed file.
                  The text can come from an actual 'abstract'
                  section in the document or will just be the
                  beginning of the document. It is stored in the
                  index so that it can be displayed inside the
                  result lists without decoding the original file.
                  The idxabsmlen parameter defines the size of the
                  stored abstract. The default value is 250 bytes.
                  The search interface gives you the choice to
                  display this stored text or a synthetic abstract
                  built by extracting text around the search terms.
                  If you always prefer the synthetic abstract, you
                  can reduce this value and save a little
                  space.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.IDXMETASTOREDLEN"
                id="RCL.INSTALL.CONFIG.RECOLLCONF.IDXMETASTOREDLEN">
                </a><span class="term"><code class=
                "varname">idxmetastoredlen</code></span></dt>
                <dd>
                  <p>Truncation length of stored metadata fields.
                  This does not affect indexing (the whole field is
                  processed anyway), just the amount of data stored
                  in the index for the purpose of displaying fields
                  inside result lists or previews. The default
                  value is 150 bytes which may be too low if you
                  have custom fields.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.IDXTEXTTRUNCATELEN"
                id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.IDXTEXTTRUNCATELEN"></a><span class="term"><code class="varname">idxtexttruncatelen</code></span></dt>
                <dd>
                  <p>Truncation length for all document texts. Only
                  index the beginning of documents. This is not
                  recommended except if you are sure that the
                  interesting keywords are at the top and have
                  severe disk space issues.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.ASPELLLANGUAGE" id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.ASPELLLANGUAGE"></a><span class="term"><code class="varname">aspellLanguage</code></span></dt>
                <dd>
                  <p>Language definitions to use when creating the
                  aspell dictionary. The value must match a set of
                  aspell language definition files. You can type
                  "aspell dicts" to see a list The default if this
                  is not set is to use the NLS environment to guess
                  the value.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.ASPELLADDCREATEPARAM"
                id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.ASPELLADDCREATEPARAM">
                </a><span class="term"><code class=
                "varname">aspellAddCreateParam</code></span></dt>
                <dd>
                  <p>Additional option and parameter to aspell
                  dictionary creation command. Some aspell packages
                  may need an additional option (e.g. on Debian
                  Jessie: --local-data-dir=/usr/lib/aspell). See
                  Debian bug 772415.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.ASPELLKEEPSTDERR"
                id="RCL.INSTALL.CONFIG.RECOLLCONF.ASPELLKEEPSTDERR">
                </a><span class="term"><code class=
                "varname">aspellKeepStderr</code></span></dt>
                <dd>
                  <p>Set this to have a look at aspell dictionary
                  creation errors. There are always many, so this
                  is mostly for debugging.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.NOASPELL" id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.NOASPELL"></a><span class="term"><code class="varname">noaspell</code></span></dt>
                <dd>
                  <p>Disable aspell use. The aspell dictionary
                  generation takes time, and some combinations of
                  aspell version, language, and local terms, result
                  in aspell crashing, so it sometimes makes sense
                  to just disable the thing.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.MONAUXINTERVAL" id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.MONAUXINTERVAL"></a><span class="term"><code class="varname">monauxinterval</code></span></dt>
                <dd>
                  <p>Auxiliary database update interval. The real
                  time indexer only updates the auxiliary databases
                  (stemdb, aspell) periodically, because it would
                  be too costly to do it for every document change.
                  The default period is one hour.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.MONIXINTERVAL" id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.MONIXINTERVAL"></a><span class="term"><code class="varname">monixinterval</code></span></dt>
                <dd>
                  <p>Minimum interval (seconds) between processings
                  of the indexing queue. The real time indexer does
                  not process each event when it comes in, but lets
                  the queue accumulate, to diminish overhead and to
                  aggregate multiple events affecting the same
                  file. Default 30 S.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.MONDELAYPATTERNS"
                id="RCL.INSTALL.CONFIG.RECOLLCONF.MONDELAYPATTERNS">
                </a><span class="term"><code class=
                "varname">mondelaypatterns</code></span></dt>
                <dd>
                  <p>Timing parameters for the real time indexing.
                  Definitions for files which get a longer delay
                  before reindexing is allowed. This is for
                  fast-changing files, that should only be
                  reindexed once in a while. A list of
                  wildcardPattern:seconds pairs. The patterns are
                  matched with fnmatch(pattern, path, 0) You can
                  quote entries containing white space with double
                  quotes (quote the whole entry, not the pattern).
                  The default is empty. Example: mondelaypatterns =
                  *.log:20 "*with spaces.*:30"</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.MONIONICECLASS" id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.MONIONICECLASS"></a><span class="term"><code class="varname">monioniceclass</code></span></dt>
                <dd>
                  <p>ionice class for the real time indexing
                  process On platforms where this is supported. The
                  default value is 3.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.MONIONICECLASSDATA"
                id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.MONIONICECLASSDATA"></a><span class="term"><code class="varname">monioniceclassdata</code></span></dt>
                <dd>
                  <p>ionice class parameter for the real time
                  indexing process. On platforms where this is
                  supported. The default is empty.</p>
                </dd>
              </dl>
            </div>
          </div>
          <div class="sect3">
            <div class="titlepage">
              <div>
                <div>
                  <h4 class="title"><a name=
                  "RCL.INSTALL.CONFIG.RECOLLCONF.QUERY" id=
                  "RCL.INSTALL.CONFIG.RECOLLCONF.QUERY"></a>6.4.2.6.&nbsp;Query-time
                  parameters (no impact on the index)</h4>
                </div>
              </div>
            </div>
            <div class="variablelist">
              <dl class="variablelist">
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.AUTODIACSENS" id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.AUTODIACSENS"></a><span class="term"><code class="varname">autodiacsens</code></span></dt>
                <dd>
                  <p>auto-trigger diacritics sensitivity (raw index
                  only). IF the index is not stripped, decide if we
                  automatically trigger diacritics sensitivity if
                  the search term has accented characters (not in
                  unac_except_trans). Else you need to use the
                  query language and the "D" modifier to specify
                  diacritics sensitivity. Default is no.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.AUTOCASESENS" id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.AUTOCASESENS"></a><span class="term"><code class="varname">autocasesens</code></span></dt>
                <dd>
                  <p>auto-trigger case sensitivity (raw index
                  only). IF the index is not stripped (see
                  indexStripChars), decide if we automatically
                  trigger character case sensitivity if the search
                  term has upper-case characters in any but the
                  first position. Else you need to use the query
                  language and the "C" modifier to specify
                  character-case sensitivity. Default is yes.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.MAXTERMEXPAND" id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.MAXTERMEXPAND"></a><span class="term"><code class="varname">maxTermExpand</code></span></dt>
                <dd>
                  <p>Maximum query expansion count for a single
                  term (e.g.: when using wildcards). This only
                  affects queries, not indexing. We used to not
                  limit this at all (except for filenames where the
                  limit was too low at 1000), but it is
                  unreasonable with a big index. Default 10000.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.MAXXAPIANCLAUSES"
                id="RCL.INSTALL.CONFIG.RECOLLCONF.MAXXAPIANCLAUSES">
                </a><span class="term"><code class=
                "varname">maxXapianClauses</code></span></dt>
                <dd>
                  <p>Maximum number of clauses we add to a single
                  Xapian query. This only affects queries, not
                  indexing. In some cases, the result of term
                  expansion can be multiplicative, and we want to
                  avoid eating all the memory. Default 50000.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.SNIPPETMAXPOSWALK"
                id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.SNIPPETMAXPOSWALK"></a><span class="term"><code class="varname">snippetMaxPosWalk</code></span></dt>
                <dd>
                  <p>Maximum number of positions we walk while
                  populating a snippet for the result list. The
                  default of 1,000,000 may be insufficient for very
                  big documents, the consequence would be snippets
                  with possibly meaning-altering missing words.</p>
                </dd>
              </dl>
            </div>
          </div>
          <div class="sect3">
            <div class="titlepage">
              <div>
                <div>
                  <h4 class="title"><a name=
                  "RCL.INSTALL.CONFIG.RECOLLCONF.PDF" id=
                  "RCL.INSTALL.CONFIG.RECOLLCONF.PDF"></a>6.4.2.7.&nbsp;Parameters
                  for the PDF input script</h4>
                </div>
              </div>
            </div>
            <div class="variablelist">
              <dl class="variablelist">
                <dt><a name="RCL.INSTALL.CONFIG.RECOLLCONF.PDFOCR"
                id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.PDFOCR"></a><span class="term"><code class="varname">pdfocr</code></span></dt>
                <dd>
                  <p>Attempt OCR of PDF files with no text content
                  if both tesseract and pdftoppm are installed. The
                  default is off because OCR is so very slow.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.PDFOCRLANG" id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.PDFOCRLANG"></a><span class="term"><code class="varname">pdfocrlang</code></span></dt>
                <dd>
                  <p>Language to assume for PDF OCR. This is very
                  important for having a reasonable rate of errors
                  with tesseract. This can also be set through a
                  configuration variable or directory-local
                  parameters. See the rclpdf.py script.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.PDFATTACH" id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.PDFATTACH"></a><span class="term"><code class="varname">pdfattach</code></span></dt>
                <dd>
                  <p>Enable PDF attachment extraction by executing
                  pdftk (if available). This is normally disabled,
                  because it does slow down PDF indexing a bit even
                  if not one attachment is ever found.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.PDFEXTRAMETA" id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.PDFEXTRAMETA"></a><span class="term"><code class="varname">pdfextrameta</code></span></dt>
                <dd>
                  <p>Extract text from selected XMP metadata tags.
                  This is a space-separated list of qualified XMP
                  tag names. Each element can also include a
                  translation to a Recoll field name, separated by
                  a '|' character. If the second element is absent,
                  the tag name is used as the Recoll field names.
                  You will also need to add specifications to the
                  'fields' file to direct processing of the
                  extracted data.</p>
                </dd>
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.PDFEXTRAMETAFIX" id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.PDFEXTRAMETAFIX"></a><span class="term"><code class="varname">pdfextrametafix</code></span></dt>
                <dd>
                  <p>Define name of XMP field editing script. This
                  defines the name of a script to be loaded for
                  editing XMP field values. The script should
                  define a 'MetaFixer' class with a metafix()
                  method which will be called with the qualified
                  tag name and value of each selected field, for
                  editing or erasing. A new instance is created for
                  each document, so that the object can keep state
                  for, e.g. eliminating duplicate values.</p>
                </dd>
              </dl>
            </div>
          </div>
          <div class="sect3">
            <div class="titlepage">
              <div>
                <div>
                  <h4 class="title"><a name=
                  "RCL.INSTALL.CONFIG.RECOLLCONF.SPECLOCATIONS" id=
                  "RCL.INSTALL.CONFIG.RECOLLCONF.SPECLOCATIONS"></a>6.4.2.8.&nbsp;Parameters
                  set for specific locations</h4>
                </div>
              </div>
            </div>
            <div class="variablelist">
              <dl class="variablelist">
                <dt><a name=
                "RCL.INSTALL.CONFIG.RECOLLCONF.MHMBOXQUIRKS" id=
                "RCL.INSTALL.CONFIG.RECOLLCONF.MHMBOXQUIRKS"></a><span class="term"><code class="varname">mhmboxquirks</code></span></dt>
                <dd>
                  <p>Enable thunderbird/mozilla-seamonkey mbox
                  format quirks Set this for the directory where
                  the email mbox files are stored.</p>
                </dd>
              </dl>
            </div>
          </div>
        </div>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name=
                "RCL.INSTALL.CONFIG.FIELDS" id=
                "RCL.INSTALL.CONFIG.FIELDS"></a>6.4.3.&nbsp;The
                fields file</h3>
              </div>
            </div>
          </div>
          <p>This file contains information about dynamic fields
          handling in <span class="application">Recoll</span>. Some
          very basic fields have hard-wired behaviour, and, mostly,
          you should not change the original data inside the
          <code class="filename">fields</code> file. But you can
          create custom fields fitting your data and handle them
          just like they were native ones.</p>
          <p>The <code class="filename">fields</code> file has
          several sections, which each define an aspect of fields
          processing. Quite often, you'll have to modify several
          sections to obtain the desired behaviour.</p>
          <p>We will only give a short description here, you should
          refer to the comments inside the default file for more
          detailed information.</p>
          <p>Field names should be lowercase alphabetic ASCII.</p>
          <div class="variablelist">
            <dl class="variablelist">
              <dt><span class="term">[prefixes]</span></dt>
              <dd>
                <p>A field becomes indexed (searchable) by having a
                prefix defined in this section. There is a more
                complete explanation of what prefixes are in used
                by a standard recoll installation. In a nutshell:
                extension prefixes should be all caps, begin with
                XY, and short. E.g. XYMFLD.</p>
              </dd>
              <dt><span class="term">[values]</span></dt>
              <dd>
                <p>Fields listed in this section will be stored as
                <span class="application">Xapian</span>
                <code class="literal">values</code> inside the
                index. This makes them available for range queries,
                allowing to filter results according to the field
                value. This feature currently supports string and
                integer data. See the comments in the file for more
                detail</p>
              </dd>
              <dt><span class="term">[stored]</span></dt>
              <dd>
                <p>A field becomes stored (displayable inside
                results) by having its name listed in this section
                (typically with an empty value).</p>
              </dd>
              <dt><span class="term">[aliases]</span></dt>
              <dd>
                <p>This section defines lists of synonyms for the
                canonical names used inside the <code class=
                "literal">[prefixes]</code> and <code class=
                "literal">[stored]</code> sections</p>
              </dd>
              <dt><span class="term">[queryaliases]</span></dt>
              <dd>
                <p>This section also defines aliases for the
                canonic field names, with the difference that the
                substitution will only be used at query time,
                avoiding any possibility that the value would
                pick-up random metadata from documents.</p>
              </dd>
              <dt><span class="term">handler-specific
              sections</span></dt>
              <dd>
                <p>Some input handlers may need specific
                configuration for handling fields. Only the email
                message handler currently has such a section (named
                <code class="literal">[mail]</code>). It allows
                indexing arbitrary email headers in addition to the
                ones indexed by default. Other such sections may
                appear in the future.</p>
              </dd>
            </dl>
          </div>
          <p>Here follows a small example of a personal
          <code class="filename">fields</code> file. This would
          extract a specific email header and use it as a
          searchable field, with data displayable inside result
          lists. (Side note: as the email handler does no decoding
          on the values, only plain ascii headers can be indexed,
          and only the first occurrence will be used for headers
          that occur several times).</p>
          <pre class="programlisting">[prefixes]
        # Index mailmytag contents (with the given prefix)
        mailmytag = XMTAG

        [stored]
        # Store mailmytag inside the document data record (so that it can be
        # displayed - as %(mailmytag) - in result lists).
        mailmytag = 

        [queryaliases]
        filename = fn
        containerfilename = cfn

        [mail]
        # Extract the X-My-Tag mail header, and use it internally with the
        # mailmytag field name
        x-my-tag = mailmytag
        </pre>
          <div class="sect3">
            <div class="titlepage">
              <div>
                <div>
                  <h4 class="title"><a name=
                  "RCL.INSTALL.CONFIG.FIELDS.XATTR" id=
                  "RCL.INSTALL.CONFIG.FIELDS.XATTR"></a>6.4.3.1.&nbsp;Extended
                  attributes in the fields file</h4>
                </div>
              </div>
            </div>
            <p><span class="application">Recoll</span> versions
            1.19 and later process user extended file attributes as
            documents fields by default.</p>
            <p>Attributes are processed as fields of the same name,
            after removing the <code class="literal">user</code>
            prefix on Linux.</p>
            <p>The <code class="literal">[xattrtofields]</code>
            section of the <code class="filename">fields</code>
            file allows specifying translations from extended
            attributes names to <span class=
            "application">Recoll</span> field names. An empty
            translation disables use of the corresponding attribute
            data.</p>
          </div>
        </div>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name=
                "RCL.INSTALL.CONFIG.MIMEMAP" id=
                "RCL.INSTALL.CONFIG.MIMEMAP"></a>6.4.4.&nbsp;The
                mimemap file</h3>
              </div>
            </div>
          </div>
          <p><code class="filename">mimemap</code> specifies the
          file name extension to MIME type mappings.</p>
          <p>For file names without an extension, or with an
          unknown one, a system command (<span class=
          "command"><strong>file</strong></span> <code class=
          "option">-i</code>, or <span class=
          "command"><strong>xdg-mime</strong></span>) will be
          executed to determine the MIME type (this can be switched
          off, or the command changed inside the main configuration
          file).</p>
          <p>All extension values in <code class=
          "filename">mimemap</code> must be entered in lower case.
          File names extensions are lower-cased for comparison
          during indexing, meaning that an upper case <code class=
          "filename">mimemap</code> entry will never be
          matched.</p>
          <p>The mappings can be specified on a per-subtree basis,
          which may be useful in some cases. Example: <span class=
          "application">okular</span> notes have a <code class=
          "filename">.xml</code> extension but should be handled
          specially, which is possible because they are usually all
          located in one place. Example:</p>
          <pre class="programlisting">
          [~/.kde/share/apps/okular/docdata]
        .xml = application/x-okular-notes</pre>
          <p>The <code class="varname">recoll_noindex</code>
          <code class="filename">mimemap</code> variable has been
          moved to <code class="filename">recoll.conf</code> and
          renamed to <code class=
          "varname">noContentSuffixes</code>, while keeping the
          same function, as of <span class=
          "application">Recoll</span> version 1.21. For older
          <span class="application">Recoll</span> versions, see the
          documentation for <code class=
          "varname">noContentSuffixes</code> but use <code class=
          "varname">recoll_noindex</code> in <code class=
          "filename">mimemap</code>.</p>
        </div>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name=
                "RCL.INSTALL.CONFIG.MIMECONF" id=
                "RCL.INSTALL.CONFIG.MIMECONF"></a>6.4.5.&nbsp;The
                mimeconf file</h3>
              </div>
            </div>
          </div>
          <p>The main purpose of the <code class=
          "filename">mimeconf</code> file is to specify how the
          different MIME types are handled for indexing. This is
          done in the <code class="literal">[index]</code> section,
          which should not be modified casually. See the comments
          in the file.</p>
          <p>The file also contains other definitions which affect
          the query language and the GUI, and which, in retrospect,
          should have been stored elsewhere.</p>
          <p>The <code class="literal">[icons]</code> section
          allows you to change the icons which are displayed by the
          <span class="command"><strong>recoll</strong></span> GUI
          in the result lists (the values are the basenames of the
          <code class="literal">png</code> images inside the
          <code class="filename">iconsdir</code> directory (which
          is itself defined in <code class=
          "filename">recoll.conf</code>).</p>
          <p>The <code class="literal">[categories]</code> section
          defines the groupings of MIME types into <code class=
          "literal">categories</code> as used when adding an
          <code class="literal">rclcat</code> clause to a <a class=
          "link" href="#RCL.SEARCH.LANG" title=
          "3.6.&nbsp;The query language">query language</a> query.
          <code class="literal">rclcat</code> clauses are also used
          by the default <code class="literal">guifilters</code>
          buttons in the GUI (see next).</p>
          <p>The filter controls appear at the top of the
          <span class="command"><strong>recoll</strong></span> GUI,
          either as checkboxes just above the result list, or as a
          dropbox in the tool area.</p>
          <p>By default, they are labeled: <code class=
          "literal">media</code>, <code class=
          "literal">message</code>, <code class=
          "literal">other</code>, <code class=
          "literal">presentation</code>, <code class=
          "literal">spreadsheet</code> and <code class=
          "literal">text</code>, and each maps to a document
          category. This is determined in the <code class=
          "literal">[guifilters]</code> section, where each control
          is defined by a variable naming a query language
          fragment.</p>
          <p>A simple exemple will hopefully make things
          clearer.</p>
          <pre class="programlisting">[guifilters]

Big Books = dir:"~/My Books" size&gt;10K
My Docs = dir:"~/My Documents"
Small Books = dir:"~/My Books" size&lt;10K
System Docs = dir:/usr/share/doc
        </pre>
          <p>The above definition would create four filter
          checkboxes, labelled <code class="literal">Big
          Books</code>, <code class="literal">My Docs</code>,
          etc.</p>
          <p>The text after the equal sign must be a valid query
          language fragment, and, when the button is checked, it
          will be combined with the rest of the query with an AND
          conjunction.</p>
          <p>Any name text before a colon character will be erased
          in the display, but used for sorting. You can use this to
          display the checkboxes in any order you like. For
          exemple, the following would do exactly the same as
          above, but ordering the checkboxes in the reverse
          order.</p>
          <pre class="programlisting">[guifilters]

d:Big Books = dir:"~/My Books" size&gt;10K
c:My Docs = dir:"~/My Documents"
b:Small Books = dir:"~/My Books" size&lt;10K
a:System Docs = dir:/usr/share/doc
        </pre>
          <p>As you may have guessed, The default <code class=
          "literal">[guifilters]</code> section looks like:</p>
          <pre class="programlisting">[guifilters]
text = rclcat:text
spreadsheet = rclcat:spreadsheet
presentation = rclcat:presentation
media = rclcat:media
message = rclcat:message
other = rclcat:other
        </pre>
        </div>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name=
                "RCL.INSTALL.CONFIG.MIMEVIEW" id=
                "RCL.INSTALL.CONFIG.MIMEVIEW"></a>6.4.6.&nbsp;The
                mimeview file</h3>
              </div>
            </div>
          </div>
          <p><code class="filename">mimeview</code> specifies which
          programs are started when you click on an <span class=
          "guilabel">Open</span> link in a result list. Ie: HTML is
          normally displayed using <span class=
          "application">firefox</span>, but you may prefer
          <span class="application">Konqueror</span>, your
          <span class="application">openoffice.org</span> program
          might be named <span class=
          "command"><strong>oofice</strong></span> instead of
          <span class="command"><strong>openoffice</strong></span>
          etc.</p>
          <p>Changes to this file can be done by direct editing, or
          through the <span class=
          "command"><strong>recoll</strong></span> GUI preferences
          dialog.</p>
          <p>If <span class="guilabel">Use desktop preferences to
          choose document editor</span> is checked in the
          <span class="application">Recoll</span> GUI preferences,
          all <code class="filename">mimeview</code> entries will
          be ignored except the one labelled <code class=
          "literal">application/x-all</code> (which is set to use
          <span class="command"><strong>xdg-open</strong></span> by
          default).</p>
          <p>In this case, the <code class=
          "literal">xallexcepts</code> top level variable defines a
          list of MIME type exceptions which will be processed
          according to the local entries instead of being passed to
          the desktop. This is so that specific <span class=
          "application">Recoll</span> options such as a page number
          or a search string can be passed to applications that
          support them, such as the <span class=
          "application">evince</span> viewer.</p>
          <p>As for the other configuration files, the normal usage
          is to have a <code class="filename">mimeview</code>
          inside your own configuration directory, with just the
          non-default entries, which will override those from the
          central configuration file.</p>
          <p>All viewer definition entries must be placed under a
          <code class="literal">[view]</code> section.</p>
          <p>The keys in the file are normally MIME types. You can
          add an application tag to specialize the choice for an
          area of the filesystem (using a <code class=
          "varname">localfields</code> specification in
          <code class="filename">mimeconf</code>). The syntax for
          the key is <em class=
          "replaceable"><code>mimetype</code></em><code class=
          "literal">|</code><em class=
          "replaceable"><code>tag</code></em></p>
          <p>The <code class="varname">nouncompforviewmts</code>
          entry, (placed at the top level, outside of the
          <code class="literal">[view]</code> section), holds a
          list of MIME types that should not be uncompressed before
          starting the viewer (if they are found compressed, ie:
          <em class=
          "replaceable"><code>mydoc.doc.gz</code></em>).</p>
          <p>The right side of each assignment holds a command to
          be executed for opening the file. The following
          substitutions are performed:</p>
          <div class="itemizedlist">
            <ul class="itemizedlist" style=
            "list-style-type: disc;">
              <li class="listitem">
                <p><b>%D.&nbsp;</b>Document date</p>
              </li>
              <li class="listitem">
                <p><b>%f.&nbsp;</b>File name. This may be the name
                of a temporary file if it was necessary to create
                one (ie: to extract a subdocument from a
                container).</p>
              </li>
              <li class="listitem">
                <p><b>%i.&nbsp;</b>Internal path, for subdocuments
                of containers. The format depends on the container
                type. If this appears in the command line,
                <span class="application">Recoll</span> will not
                create a temporary file to extract the subdocument,
                expecting the called application (possibly a
                script) to be able to handle it.</p>
              </li>
              <li class="listitem">
                <p><b>%M.&nbsp;</b>MIME type</p>
              </li>
              <li class="listitem">
                <p><b>%p.&nbsp;</b>Page index. Only significant for
                a subset of document types, currently only PDF,
                Postscript and DVI files. Can be used to start the
                editor at the right page for a match or
                snippet.</p>
              </li>
              <li class="listitem">
                <p><b>%s.&nbsp;</b>Search term. The value will only
                be set for documents with indexed page numbers (ie:
                PDF). The value will be one of the matched search
                terms. It would allow pre-setting the value in the
                "Find" entry inside Evince for example, for easy
                highlighting of the term.</p>
              </li>
              <li class="listitem">
                <p><b>%u.&nbsp;</b>Url.</p>
              </li>
            </ul>
          </div>
          <p>In addition to the predefined values above, all
          strings like <code class="literal">%(fieldname)</code>
          will be replaced by the value of the field named
          <code class="literal">fieldname</code> for the document.
          This could be used in combination with field
          customisation to help with opening the document.</p>
        </div>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name=
                "RCL.INSTALL.CONFIG.PTRANS" id=
                "RCL.INSTALL.CONFIG.PTRANS"></a>6.4.7.&nbsp;The
                <code class="filename">ptrans</code> file</h3>
              </div>
            </div>
          </div>
          <p><code class="filename">ptrans</code> specifies
          query-time path translations. These can be useful in
          <a class="link" href="#RCL.SEARCH.PTRANS" title=
          "3.5.&nbsp;Path translations">multiple cases</a>.</p>
          <p>The file has a section for any index which needs
          translations, either the main one or additional query
          indexes. The sections are named with the <span class=
          "application">Xapian</span> index directory names. No
          slash character should exist at the end of the paths (all
          comparisons are textual). An exemple should make things
          sufficiently clear</p>
          <pre class="programlisting">
          [/home/me/.recoll/xapiandb]
          /this/directory/moved = /to/this/place

          [/path/to/additional/xapiandb]
          /server/volume1/docdir = /net/server/volume1/docdir
          /server/volume2/docdir = /net/server/volume2/docdir
        </pre>
        </div>
        <div class="sect2">
          <div class="titlepage">
            <div>
              <div>
                <h3 class="title"><a name=
                "RCL.INSTALL.CONFIG.EXAMPLES" id=
                "RCL.INSTALL.CONFIG.EXAMPLES"></a>6.4.8.&nbsp;Examples
                of configuration adjustments</h3>
              </div>
            </div>
          </div>
          <div class="sect3">
            <div class="titlepage">
              <div>
                <div>
                  <h4 class="title"><a name=
                  "RCL.INSTALL.CONFIG.EXAMPLES.ADDVIEW" id=
                  "RCL.INSTALL.CONFIG.EXAMPLES.ADDVIEW"></a>6.4.8.1.&nbsp;Adding
                  an external viewer for an non-indexed type</h4>
                </div>
              </div>
            </div>
            <p>Imagine that you have some kind of file which does
            not have indexable content, but for which you would
            like to have a functional <span class=
            "guilabel">Open</span> link in the result list (when
            found by file name). The file names end in <em class=
            "replaceable"><code>.blob</code></em> and can be
            displayed by application <em class=
            "replaceable"><code>blobviewer</code></em>.</p>
            <p>You need two entries in the configuration files for
            this to work:</p>
            <div class="itemizedlist">
              <ul class="itemizedlist" style=
              "list-style-type: disc;">
                <li class="listitem">
                  <p>In <code class=
                  "filename">$RECOLL_CONFDIR/mimemap</code>
                  (typically <code class=
                  "filename">~/.recoll/mimemap</code>), add the
                  following line:</p>
                  <pre class="programlisting">
            .blob = application/x-blobapp
          </pre>
                  <p>Note that the MIME type is made up here, and
                  you could call it <em class=
                  "replaceable"><code>diesel/oil</code></em> just
                  the same.</p>
                </li>
                <li class="listitem">
                  <p>In <code class=
                  "filename">$RECOLL_CONFDIR/mimeview</code> under
                  the <code class="literal">[view]</code> section,
                  add:</p>
                  <pre class="programlisting">
              application/x-blobapp = blobviewer %f
            </pre>
                  <p>We are supposing that <em class=
                  "replaceable"><code>blobviewer</code></em> wants
                  a file name parameter here, you would use
                  <code class="literal">%u</code> if it liked URLs
                  better.</p>
                </li>
              </ul>
            </div>
            <p>If you just wanted to change the application used by
            <span class="application">Recoll</span> to display a
            MIME type which it already knows, you would just need
            to edit <code class="filename">mimeview</code>. The
            entries you add in your personal file override those in
            the central configuration, which you do not need to
            alter. <code class="filename">mimeview</code> can also
            be modified from the Gui.</p>
          </div>
          <div class="sect3">
            <div class="titlepage">
              <div>
                <div>
                  <h4 class="title"><a name=
                  "RCL.INSTALL.CONFIG.EXAMPLES.ADDINDEX" id=
                  "RCL.INSTALL.CONFIG.EXAMPLES.ADDINDEX"></a>6.4.8.2.&nbsp;Adding
                  indexing support for a new file type</h4>
                </div>
              </div>
            </div>
            <p>Let us now imagine that the above <em class=
            "replaceable"><code>.blob</code></em> files actually
            contain indexable text and that you know how to extract
            it with a command line program. Getting <span class=
            "application">Recoll</span> to index the files is easy.
            You need to perform the above alteration, and also to
            add data to the <code class="filename">mimeconf</code>
            file (typically in <code class=
            "filename">~/.recoll/mimeconf</code>):</p>
            <div class="itemizedlist">
              <ul class="itemizedlist" style=
              "list-style-type: disc;">
                <li class="listitem">
                  <p>Under the <code class="literal">[index]</code>
                  section, add the following line (more about the
                  <em class="replaceable"><code>rclblob</code></em>
                  indexing script later):</p>
                  <pre class="programlisting">
application/x-blobapp = exec rclblob</pre>
                  <p>Or if the files are mostly text and you don't
                  need to process them for indexing:</p>
                  <pre class="programlisting">
application/x-blobapp = internal text/plain</pre>
                </li>
                <li class="listitem">
                  <p>Under the <code class="literal">[icons]</code>
                  section, you should choose an icon to be
                  displayed for the files inside the result lists.
                  Icons are normally 64x64 pixels PNG files which
                  live in <code class=
                  "filename">/usr/share/recoll/images</code>.</p>
                </li>
                <li class="listitem">
                  <p>Under the <code class=
                  "literal">[categories]</code> section, you should
                  add the MIME type where it makes sense (you can
                  also create a category). Categories may be used
                  for filtering in advanced search.</p>
                </li>
              </ul>
            </div>
            <p>The <em class=
            "replaceable"><code>rclblob</code></em> handler should
            be an executable program or script which exists inside
            <code class=
            "filename">/usr/share/recoll/filters</code>. It will be
            given a file name as argument and should output the
            text or html contents on the standard output.</p>
            <p>The <a class="link" href="#RCL.PROGRAM.FILTERS"
            title=
            "5.1.&nbsp;Writing a document input handler">filter
            programming</a> section describes in more detail how to
            write an input handler.</p>
          </div>
        </div>
      </div>
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